drm/arcpgu: Drop transitional hooks

These do absolutely nothing for atomic drivers.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Alexey Brodkin <abrodkin@synopsys.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181004202446.22905-9-daniel.vetter@ffwll.ch

drivers/gpu/drm/arc/arcpgu_crtc.c

@@ -158,8 +158,6 @@ static void arc_pgu_crtc_atomic_begin(struct drm_crtc *crtc,
 
 static const struct drm_crtc_helper_funcs arc_pgu_crtc_helper_funcs = {
 	.mode_valid	= arc_pgu_crtc_mode_valid,
-	.mode_set	= drm_helper_crtc_mode_set,
-	.mode_set_base	= drm_helper_crtc_mode_set_base,
 	.mode_set_nofb	= arc_pgu_crtc_mode_set_nofb,
 	.atomic_begin	= arc_pgu_crtc_atomic_begin,
 	.atomic_enable	= arc_pgu_crtc_atomic_enable,