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/r128/r128_drv.c

@@ -56,7 +56,6 @@ static struct drm_driver driver = {
 	.irq_uninstall = r128_driver_irq_uninstall,
 	.irq_handler = r128_driver_irq_handler,
 	.reclaim_buffers = drm_core_reclaim_buffers,
-	.get_reg_ofs = drm_core_get_reg_ofs,
 	.ioctls = r128_ioctls,
 	.dma_ioctl = r128_cce_buffers,
 	.fops = {