s390/facilities: cleanup PFMF and HPAGE machine facility detection

MACHINE_HAS_PFMF and MACHINE_HAS_HPAGE actually have the same semantics:
the cpu has the EDAT1 facility installed in zArch mode. So remove one
of the feature flags in machine_flags and rename the other one to EDAT1.

The two old macros simply get mapped to MACHINE_HAS_EDAT1.

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