s390: fix typo in syscall_wrapper.h

Looks like this endif comment was erroneously unchanged when copied over
from the x86 version.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Link: https://lore.kernel.org/r/20220304090109.29386-1-ruscur@russell.cc


Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>