drm: kill get_reg_ofs callback

Every driver used the default implementation. Fold that one into
the only callsite and drop the callback.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/vmwgfx/vmwgfx_drv.c

@@ -723,7 +723,6 @@ static struct drm_driver driver = {
 	.irq_uninstall = vmw_irq_uninstall,
 	.irq_handler = vmw_irq_handler,
 	.reclaim_buffers_locked = NULL,
-	.get_reg_ofs = drm_core_get_reg_ofs,
 	.ioctls = vmw_ioctls,
 	.num_ioctls = DRM_ARRAY_SIZE(vmw_ioctls),
 	.dma_quiescent = NULL,	/*vmw_dma_quiescent, */