s390/uaccess: avoid __ashlti3() call

s390/uaccess: avoid __ashlti3() call

__cmpxchg_user_key() uses 128 bit types which, depending on compiler
and config options, may lead to an __ashlti3() library call.

Get rid of that by simply casting the 128 bit values to 32 bit values.

Reported-by: kernel test robot <[email protected]>
Suggested-by: Janis Schoetterl-Glausch <[email protected]>
Fixes: 51098f0eb22e ("s390/cmpxchg: make loop condition for 1,2 byte cases precise")
Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Heiko Carstens <[email protected]>