thp, s390: add missing earlyclobber to inline assembly

thp, s390: add missing earlyclobber to inline assembly

The constraints of the rrbm inline assembly are missing two
earlyclobber operands, which can lead to an addressing exception
depending on compiler register allocation decisions.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>