drm/sun4i: Make sun4i_crtc_init return ERR_PTR style error codes

sun4i_crtc_init can fail for a number of reasons. Instead of returning
a NULL pointer when it fails, pass back the encountered error using
ERR_PTR.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/drivers/gpu/drm/sun4i/sun4i_crtc.c b/drivers/gpu/drm/sun4i/sun4i_crtc.c
index a5d546a..7d332fc 100644
--- a/drivers/gpu/drm/sun4i/sun4i_crtc.c
+++ b/drivers/gpu/drm/sun4i/sun4i_crtc.c
@@ -145,7 +145,7 @@ struct sun4i_crtc *sun4i_crtc_init(struct drm_device *drm)
 
 	scrtc = devm_kzalloc(drm->dev, sizeof(*scrtc), GFP_KERNEL);
 	if (!scrtc)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 	scrtc->drv = drv;
 
 	ret = drm_crtc_init_with_planes(drm, &scrtc->crtc,
@@ -155,7 +155,7 @@ struct sun4i_crtc *sun4i_crtc_init(struct drm_device *drm)
 					NULL);
 	if (ret) {
 		dev_err(drm->dev, "Couldn't init DRM CRTC\n");
-		return NULL;
+		return ERR_PTR(ret);
 	}
 
 	drm_crtc_helper_add(&scrtc->crtc, &sun4i_crtc_helper_funcs);