drm/rockchip: Use drm_crtc_mask()

Use drm_crtc_mask() where appropriate.

Cc: Sandy Huang <hjc@rock-chips.com>
Cc: "Heiko Stübner" <heiko@sntech.de>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20180626194716.12522-7-ville.syrjala@linux.intel.com

drivers/gpu/drm/rockchip/rockchip_drm_vop.c

@@ -1308,7 +1308,7 @@ static int vop_create_crtc(struct vop *vop)
 	for (i = 0; i < vop_data->win_size; i++) {
 		struct vop_win *vop_win = &vop->win[i];
 		const struct vop_win_data *win_data = vop_win->data;
-		unsigned long possible_crtcs = 1 << drm_crtc_index(crtc);
+		unsigned long possible_crtcs = drm_crtc_mask(crtc);
 
 		if (win_data->type != DRM_PLANE_TYPE_OVERLAY)
 			continue;