MFC r261917, r261918, r261919, r261920, r261921, r261922

MFC r261917, r261918, r261919, r261920, r261921, r261922

  Always clear L1 PTE descriptor when removing superpage on ARM

  Invalidate L1 PTE regardles of existance of the corresponding l2_bucket.

  Ensure proper TLB invalidation on superpage promotion and demotion on ARM

  Base pages within newly created superpage need to be invalidated so that
  new mapping is "visible" immediately after creation.

  Fix superpage promotion on ARM with respect to RO/RW and wired attributes

  Avoid redundant superpage promotion attempts on ARM

  Remove spurious assertion from pmap_extract_locked() on ARM

  Handle pmap_enter() on already promoted mappings for ARMv6/v7

git-svn-id: svn://svn.freebsd.org/base/stable/10@266199 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f