arm64: Kconfig: select HAVE_FUTEX_CMPXCHG

mainline inclusion
from mainline-v5.6-rc1
commit 98346023
category: bugfix
bugzilla: 28680
CVE: NA

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arm64 provides always working implementation of futex_atomic_cmpxchg_inatomic(),
so there is no need to check it runtime.

Reported-by: Piyush swami <Piyush.swami@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Conflicts:
	arch/arm64/Kconfig

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>