MFC 265694, 265705, 265784:

MFC 265694, 265705, 265784:

  Move the mptramp code which is specific to the Marvell ArmadaXP SoC out of
  the common locore.S file and into the mv/armadaxp directory.

  Consolidate all the AP core startup stuff under a single #ifdef SMP block

  Call idcache_inv_all from the AP core entry code before turning on the MMU.
  Also, enable instruction and branch caches, which should be safe now that
  they're properly initialized/invalidated first.

git-svn-id: svn://svn.freebsd.org/base/stable/10@266385 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f