arm64 provides always working implementation of futex_atomic_cmpxchg_inatomic(),
so there is no need to check it runtime.
Reported-by: NPiyush swami <Piyush.swami@arm.com>
Signed-off-by: NVladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>