Move PD_MASK, PT_MASK and a couple macros into pmap.c. The only other

Move PD_MASK, PT_MASK and a couple macros into pmap.c. The only other
user of these was hibernate, which now gets its own PD_MASK (since
the resume time PD_MASK is essentially disjoint from the runtime
PD_MASK). No functional change, just moving the deck chairs around in
preparation for an upcoming change.

ok deraadt