Commit 2e07c249a6 (kconfig: arm: introduce symbol for ARM CPUs)
collected the default values of CONFIG_SYS_CPU into arch/arm/Kconfig.
This commit moves "armv8" to there for consistency.
Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Georges Savoundararadj <savoundg@gmail.com>