s390/bitops: return true/false (not 1/0) from bool functions

Signed-off-by: Huilong Deng <denghuilong@cdjrlc.com>
Link: https://lore.kernel.org/r/20211017092057.24179-1-denghuilong@cdjrlc.com


Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>