Add a common drm_driver.dumb_map_offset function for GEM backed drivers.
Signed-off-by: NNoralf Trønnes <noralf@tronnes.org>
Reviewed-by: NPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: NSean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1500837417-40580-2-git-send-email-noralf@tronnes.org