drm/vmwgfx: Make surfaces prime-aware

Add prime exporting and imporing operations to surfaces

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>

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

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