KVM: s390/mm: Properly reset no-dat

When the CMMA state needs to be reset, the no-dat bit also needs to be
reset. Failure to do so could cause issues in the guest, since the
guest expects the bit to be cleared after a reset.

Cc: <stable@vger.kernel.org>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Message-ID: <20231109123624.37314-1-imbrenda@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>