s390: Remove 'message security assist' from the list of vital facilities

The code in arch/s390/crypto checks for the availability of the
'message security assist' facility on its own, either by using
module_cpu_feature_match(MSA, ...) or by checking the facility
bit during cpacf_query(). Thus setting the MSA facility bit in
gen_facilities.c as hard requirement is not necessary. We can
remove it here, so that the kernel can also run on systems that
do not provide the MSA facility yet (like the emulated environment
of QEMU, for example).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>