KVM: s390: fix pfmf non-quiescing control handling

Fix the test within handle_pfmf() if the host has the NQ key-setting
facility installed.
Right now the code would incorrectly generate a program check in the
guest if the NQ control bit for a pfmf request was set and if the host
has the NQ key-setting facility installed.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>