cmd: booti: move CONFIG_CMD_BOOTI to Kconfig

This command is used to boot ARM64 Linux.

I made DISTRO_DEFAULTS select this option for ARM64 to respect
include/config_distro_defaults.h.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/Kconfig b/Kconfig
index cb5af5b..7c87148 100644
--- a/Kconfig
+++ b/Kconfig
@@ -58,6 +58,7 @@
 	default y if ARCH_SUNXI
 	default n
 	select CMD_BOOTZ
+	select CMD_BOOTI if ARM64
 	select CMD_DHCP
 	select CMD_EXT2
 	select CMD_EXT4