Fix inline assembly contraints for non atomic bitops functions.

This is broken since 2.6.34 987bcdac "[S390] use inline assembly
contraints available with gcc 3.3.3".
Reported-by: NAndreas Krebbel <krebbel@linux.vnet.ibm.com>
Reported-by: NPeter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>