drm crtc: add forgotten idr cleanup functions

drm_mode_config_init initializes the idr with idr_init, so
add the missing counterparts in drm_mode_config_cleanup.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
1 file changed