s390x: query and store STFL(E) facilitites

cpacf.h will require the test_facility() function, so let's properly
query and store the STFL(E) facilities.

STFLE requires double word alignment.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20170919145033.16959-5-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>