mips: Implement basic pmap_kenter_device, pmap_kremove_device
Unbreak mips.BERI_DE4_SDROOT build, which uses device xdma. Device xdma
depends on the pmap_kenter_device APIs.
Reported by: tinderbox (local)
Sponsored by: Dell EMC Isilon
(cherry picked from commit fa3ac573a2f712393cebd195bf7331cff3d1b8fe)