s390/qdio: get rid of register asm

[ Upstream commit d3e2ff54 ]

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: 2862a2fd ("s390/qdio: fix do_sqbs() inline assembly constraint")
Signed-off-by: Sasha Levin <sashal@kernel.org>