arch/arm64: Make ARM64 stages select ARCH_ARM64

Also don't define the default as this result in spurious lines in the
.config.

The only difference in config.h is on boards with the Nvidia tegra210
SOC that now select ARCH_ARM64, because its ramstage runs in that
mode. The resulting binary is identical however.

Change-Id: Iaa9cd902281e51f823717f6ea4c72e5736fefb31
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/31315
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: HAOUAS Elyes <ehaouas@noos.fr>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/arch/arm64/Kconfig

@@ -1,27 +1,27 @@
 config ARCH_ARM64
 	bool
-	default n
 
 config ARCH_BOOTBLOCK_ARM64
 	bool
-	default n
 	select ARCH_ARM64
 	select C_ENVIRONMENT_BOOTBLOCK
 
 config ARCH_VERSTAGE_ARM64
 	bool
-	default n
+	select ARCH_ARM64
 
 config ARCH_ROMSTAGE_ARM64
 	bool
-	default n
+	select ARCH_ARM64
 
 config ARCH_RAMSTAGE_ARM64
 	bool
-	default n
+	select ARCH_ARM64
 
 source src/arch/arm64/armv8/Kconfig
 
+if ARCH_ARM64
+
 config ARM64_USE_ARCH_TIMER
 	bool
 	default n
@@ -58,3 +58,5 @@ config ARM64_A53_ERRATUM_843419
 	  incorrect address calculations in rare cases. This option enables a
 	  linker workaround to avoid those cases if your toolchain supports it.
 	  Should be selected automatically by SoCs that are affected.
+
+endif # if ARCH_ARM64

src/arch/arm64/armv8/Kconfig

@@ -1,17 +1,17 @@
 config ARCH_BOOTBLOCK_ARMV8_64
-	def_bool n
+	bool
 	select ARCH_BOOTBLOCK_ARM64
 
 config ARCH_VERSTAGE_ARMV8_64
-	def_bool n
+	bool
 	select ARCH_VERSTAGE_ARM64
 
 config ARCH_ROMSTAGE_ARMV8_64
-	def_bool n
+	bool
 	select ARCH_ROMSTAGE_ARM64
 
 config ARCH_RAMSTAGE_ARMV8_64
-	def_bool n
+	bool
 	select ARCH_RAMSTAGE_ARM64
 
 config ARCH_ARMV8_EXTENSION