s390/locking: Use arch_try_cmpxchg() instead of __atomic_cmpxchg_bool()

Use arch_try_cmpxchg() instead of __atomic_cmpxchg_bool() everywhere.
This generates the same code like before, but uses the standard
cmpxchg() implementation instead of a custom __atomic_cmpxchg_bool().

Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>