s390/mm/gmap: Fix __gmap_fault() return code

s390/mm/gmap: Fix __gmap_fault() return code

Errors in fixup_user_fault() were masked and -EFAULT was returned for
any error, including out of memory.

Fix this by returning the correct error code. This means that in many
cases the error code will be propagated all the way to userspace.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-5-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>