Convert CONFIG_SYS_I2C_LEGACY to Kconfig and add CONFIG_[ST]PL_SYS_I2C_LEGACY

First, we convert CONFIG_SYS_I2C_LEGACY to Kconfig.  Next, as you cannot
have SYS_I2C_LEGACY and DM_I2C at the same time, introduce
CONFIG_SPL_SYS_I2C_LEGACY so that we can enable the legacy option only
in SPL.  Finally, for some PowerPC cases we also need
CONFIG_TPL_SYS_I2C_LEGACY support.  Convert all of the existing users to
one or more symbols.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
index a1e1a26..3344730 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
+++ b/arch/arm/cpu/armv8/fsl-layerscape/Kconfig
@@ -121,6 +121,7 @@
 	imply ID_EEPROM
 	imply SCSI
 	imply SCSI_AHCI
+	imply SPL_SYS_I2C_LEGACY
 
 config ARCH_LS1088A
 	bool
@@ -162,6 +163,7 @@
 	select RESV_RAM if GIC_V3_ITS
 	imply ID_EEPROM
 	imply SCSI
+	imply SPL_SYS_I2C_LEGACY
 	imply PANIC_HANG
 
 config ARCH_LS2080A
@@ -215,6 +217,7 @@
 	imply DISTRO_DEFAULTS
 	imply ID_EEPROM
 	imply PANIC_HANG
+	imply SPL_SYS_I2C_LEGACY
 
 config ARCH_LX2162A
 	bool
@@ -246,6 +249,7 @@
 	imply PANIC_HANG
 	imply SCSI
 	imply SCSI_AHCI
+	imply SPL_SYS_I2C_LEGACY
 
 config ARCH_LX2160A
 	bool
@@ -280,6 +284,7 @@
 	imply PANIC_HANG
 	imply SCSI
 	imply SCSI_AHCI
+	imply SPL_SYS_I2C_LEGACY
 
 config FSL_LSCH2
 	bool