KVM: s390: Fix pfmf and conditional skey emulation

We should not return with a lock.
We also have to increase the address when we do page clearing.

Fixes: bd096f64

 ("KVM: s390: Add skey emulation fault handling")
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-Id: <20180830081355.59234-1-frankja@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>