drm/vmwgfx: Use the linux DMA api also for MOBs

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_buffer.c
Simple merge

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
Simple merge

diff --cc drivers/gpu/drm/vmwgfx/vmwgfx_mob.c
Simple merge