airoha: Add initial support for Airoha AN7581 SoC

Add initial support for Airoha AN7581 SoC. This adds the initial Kconfig
and Makefile entry for the SoC, an U-Boot specific DTSI and initial config
for it. Also add the initial code for CPU and RAM initialization.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index cf08fe6..dfeeceb 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -600,6 +600,13 @@
 	prompt "Target select"
 	default TARGET_HIKEY
 
+config ARCH_AIROHA
+	bool "Airoha SoCs"
+	select DM
+	select OF_CONTROL
+	help
+	  Support for the Airoha soc.
+
 config ARCH_AT91
 	bool "Atmel AT91"
 	select GPIO_EXTRA_HEADER
@@ -2251,6 +2258,8 @@
 	  Path within the source directory to the kwbimage.cfg file to use
 	  when packaging the U-Boot image for use.
 
+source "arch/arm/mach-airoha/Kconfig"
+
 source "arch/arm/mach-apple/Kconfig"
 
 source "arch/arm/mach-aspeed/Kconfig"