s390/qdio: get rid of register asm

[ Upstream commit d3e2ff5436d6ee38b572ba5c01dc7994769bec54 ]

Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Stable-dep-of: 2862a2fdfae8 ("s390/qdio: fix do_sqbs() inline assembly constraint")
Signed-off-by: Sasha Levin <sashal@kernel.org>