arm64: Kconfig: select HAVE_FUTEX_CMPXCHG

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

Change-Id: Id4b9ba07d979fddbdac9f2aaa5250b1487ff9042
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>
Signed-off-by: atndko <z1281552865@gmail.com>
Signed-off-by: Panchajanya1999 <panchajanya@azure-dev.live>

arch/arm64/Kconfig

@@ -125,6 +125,7 @@ config ARM64
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_REGS_AND_STACK_ACCESS_API
+	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select HAVE_RCU_TABLE_FREE
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES