Kconfig: Unify endian support option

Move SUPPORT_BIG_ENDIAN, SUPPORT_LITTLE_ENDIAN to top-level
arch Kconfig and let architectures select them as necessary.

Remove if guard for Endianness selection choice so we can
have one of SYS_BIG_ENDIAN, SYS_LITTLE_ENDIAN config symbol
defined even on single endian system.

Default endian to SYS_BIG_ENDIAN for MIPS || MICROBLAZE
and LITTLE_ENDIAN for the rest to retain old config
behaviour.

Note: PPC, SH, Xtensa are technically bi-endian, but I
checked compiled u-boot image with readelf, U-Boot currently
only support little endian for SH and Xtensa, Big Endian for
PPC.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index abd406d..8f1f466 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -8,6 +8,13 @@
 config HAVE_ARCH_IOREMAP
 	bool
 
+config SUPPORT_BIG_ENDIAN
+	bool
+
+config SUPPORT_LITTLE_ENDIAN
+	bool
+	default y if !SUPPORT_BIG_ENDIAN
+
 config SYS_CACHE_SHIFT_4
 	bool
 
@@ -59,6 +66,8 @@
 	select SUPPORT_OF_CONTROL
 	select SYS_CACHE_SHIFT_7
 	select TIMER
+	select SUPPORT_BIG_ENDIAN
+	select SUPPORT_LITTLE_ENDIAN
 	select SYS_BIG_ENDIAN if CPU_BIG_ENDIAN
 	select SYS_LITTLE_ENDIAN if !CPU_BIG_ENDIAN
 
@@ -68,6 +77,7 @@
 	select CREATE_ARCH_SYMLINK
 	select HAVE_PRIVATE_LIBGCC if !ARM64
 	select SUPPORT_ACPI
+	select SUPPORT_LITTLE_ENDIAN
 	select SUPPORT_OF_CONTROL
 
 config M68K
@@ -77,10 +87,13 @@
 	select SYS_BOOT_GET_CMDLINE
 	select SYS_BOOT_GET_KBD
 	select SYS_CACHE_SHIFT_4
+	select SUPPORT_BIG_ENDIAN
 	select SUPPORT_OF_CONTROL
 
 config MICROBLAZE
 	bool "MicroBlaze architecture"
+	select SUPPORT_BIG_ENDIAN
+	select SUPPORT_LITTLE_ENDIAN
 	select SUPPORT_OF_CONTROL
 	imply CMD_TIMER
 	imply SPL_REGMAP if SPL
@@ -101,12 +114,14 @@
 	select DM
 	select DM_EVENT
 	select OF_CONTROL
+	select SUPPORT_LITTLE_ENDIAN
 	select SUPPORT_OF_CONTROL
 	imply CMD_DM
 
 config PPC
 	bool "PowerPC architecture"
 	select HAVE_PRIVATE_LIBGCC
+	select SUPPORT_BIG_ENDIAN
 	select SUPPORT_OF_CONTROL
 	select SYS_BOOT_GET_CMDLINE
 	select SYS_BOOT_GET_KBD
@@ -115,6 +130,7 @@
 	bool "RISC-V architecture"
 	select CREATE_ARCH_SYMLINK
 	select SUPPORT_ACPI
+	select SUPPORT_LITTLE_ENDIAN
 	select SUPPORT_OF_CONTROL
 	select OF_CONTROL
 	select DM
@@ -160,6 +176,8 @@
 	select PCI_ENDPOINT
 	select SPI
 	select SUPPORT_OF_CONTROL
+	select SUPPORT_BIG_ENDIAN
+	select SUPPORT_LITTLE_ENDIAN
 	select SYSRESET_CMD_POWEROFF if CMD_POWEROFF
 	select SYS_CACHE_SHIFT_4
 	select IRQ
@@ -224,6 +242,7 @@
 
 config SH
 	bool "SuperH architecture"
+	select SUPPORT_LITTLE_ENDIAN
 	select HAVE_PRIVATE_LIBGCC
 	select SUPPORT_OF_CONTROL
 
@@ -231,6 +250,7 @@
 	bool "x86 architecture"
 	select SUPPORT_SPL
 	select SUPPORT_TPL
+	select SUPPORT_LITTLE_ENDIAN
 	select CREATE_ARCH_SYMLINK
 	select DM
 	select HAVE_ARCH_IOMAP
@@ -312,6 +332,7 @@
 config XTENSA
 	bool "Xtensa architecture"
 	select CREATE_ARCH_SYMLINK
+	select SUPPORT_LITTLE_ENDIAN
 	select SUPPORT_OF_CONTROL
 
 endchoice
@@ -515,24 +536,21 @@
 
 source "board/keymile/Kconfig"
 
-if MIPS || MICROBLAZE
-
 choice
 	prompt "Endianness selection"
+	default SYS_BIG_ENDIAN if MIPS || MICROBLAZE
+	default SYS_LITTLE_ENDIAN
 	help
-	  Some MIPS boards can be configured for either little or big endian
+	  Some boards can be configured for either little or big endian
 	  byte order. These modes require different U-Boot images. In general there
 	  is one preferred byteorder for a particular system but some systems are
 	  just as commonly used in the one or the other endianness.
 
 config SYS_BIG_ENDIAN
 	bool "Big endian"
-	depends on (SUPPORTS_BIG_ENDIAN && MIPS) || MICROBLAZE
+	depends on SUPPORT_BIG_ENDIAN
 
 config SYS_LITTLE_ENDIAN
 	bool "Little endian"
-	depends on (SUPPORTS_LITTLE_ENDIAN && MIPS) || MICROBLAZE
-
+	depends on SUPPORT_LITTLE_ENDIAN
 endchoice
-
-endif