kernel - Change vm_fault_page[_quick]() semantics + vkernel fixes

kernel - Change vm_fault_page[_quick]() semantics + vkernel fixes

* vm_fault_page[_quick]() needs to be left busied for PROT_WRITE so
  modifications made by the caller do not race other operations in the
  kernel.  Modify the API to accomodate the behavior.

* Fix procfs write race with new vm_fault_page() API.

* Fix bugs in ept_swapu32() and ept_swapu64() (vkernel + VMM)

* pmap_fault_page_quick() doesn't understand EPT page tables, have it
  fail for that case too.  This fixes bugs in vkernel + VMM mode.

* Also do some minor normalization of variables names in pmap.c

* vkernel/pmap - Use atomic_swap_long() to modify PTEs instead of a
  simple (non-atomic) assignment.

* vkernel/pmap - Fix numerous bugs in the VMM and non-VMM code for
  pmap_kenter*(), pmap_qenter*(), etc.

* vkernel/pmap - Collapse certain pmap_qremove_*() routines into the
  base pmap_qremove().