drm/imx: Use drm_plane_mask()

Use drm_plane_mask() where appropriate.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180626194716.12522-6-ville.syrjala@linux.intel.comReviewed-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: NPhilipp Zabel <p.zabel@pengutronix.de>

drivers/gpu/drm/imx/ipuv3-crtc.c

@@ -213,7 +213,7 @@ static bool ipu_crtc_mode_fixup(struct drm_crtc *crtc,
 static int ipu_crtc_atomic_check(struct drm_crtc *crtc,
 				 struct drm_crtc_state *state)
 {
-	u32 primary_plane_mask = 1 << drm_plane_index(crtc->primary);
+	u32 primary_plane_mask = drm_plane_mask(crtc->primary);
 
 	if (state->active && (primary_plane_mask & state->plane_mask) == 0)
 		return -EINVAL;