drm/exynos: do not return negative values from .get_modes()

The .get_modes() hooks aren't supposed to return negative error
codes. Return 0 for no modes, whatever the reason.

Cc: Inki Dae <inki.dae@samsung.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: stable@vger.kernel.org
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/d8665f620d9c252aa7d5a4811ff6b16e773903a2.1709913674.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/exynos/exynos_drm_vidi.c

@@ -316,14 +316,14 @@ static int vidi_get_modes(struct drm_connector *connector)
 	 */
 	if (!ctx->raw_edid) {
 		DRM_DEV_DEBUG_KMS(ctx->dev, "raw_edid is null.\n");
-		return -EFAULT;
+		return 0;
 	}
 
 	edid_len = (1 + ctx->raw_edid->extensions) * EDID_LENGTH;
 	edid = kmemdup(ctx->raw_edid, edid_len, GFP_KERNEL);
 	if (!edid) {
 		DRM_DEV_DEBUG_KMS(ctx->dev, "failed to allocate edid\n");
-		return -ENOMEM;
+		return 0;
 	}
 
 	drm_connector_update_edid_property(connector, edid);

drivers/gpu/drm/exynos/exynos_hdmi.c

@@ -887,11 +887,11 @@ static int hdmi_get_modes(struct drm_connector *connector)
 	int ret;
 
 	if (!hdata->ddc_adpt)
-		return -ENODEV;
+		return 0;
 
 	edid = drm_get_edid(connector, hdata->ddc_adpt);
 	if (!edid)
-		return -ENODEV;
+		return 0;
 
 	hdata->dvi_mode = !connector->display_info.is_hdmi;
 	DRM_DEV_DEBUG_KMS(hdata->dev, "%s : width[%d] x height[%d]\n",