Enable generic idle loop for ARM64, so can support for hlt/nohlt
command line options to override default idle loop behavior.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NLeo Yan <leo.yan@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>