kconfig: armv8: move CONFIG_ARM64 to Kconfig

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 88c7eaa..aaf800f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -4,6 +4,9 @@
 config SYS_ARCH
 	default "arm"
 
+config ARM64
+	bool
+
 choice
 	prompt "Target select"
 
@@ -459,12 +462,15 @@
 
 config TARGET_VEXPRESS_AEMV8A
 	bool "Support vexpress_aemv8a"
+	select ARM64
 
 config TARGET_LS2085A_EMU
 	bool "Support ls2085a_emu"
+	select ARM64
 
 config TARGET_LS2085A_SIMU
 	bool "Support ls2085a_simu"
+	select ARM64
 
 config TARGET_LS1021AQDS
 	bool "Support ls1021aqds_nor"
@@ -513,6 +519,8 @@
 
 endchoice
 
+source "arch/arm/cpu/armv8/Kconfig"
+
 source "arch/arm/cpu/arm926ejs/davinci/Kconfig"
 
 source "arch/arm/cpu/armv7/exynos/Kconfig"