drm/msm/dsi: check msm_dsi and dsi pointers before use

Move null checks of pointer arguments to the beginning of the
modeset init function since they are referenced immediately
instead of after they have already been used.

Signed-off-by: Lloyd Atkinson <[e-mail]>
Signed-off-by: Rob Clark <[e-mail]>

drivers/gpu/drm/msm/dsi/dsi.c

···
 	struct drm_bridge *ext_bridge;
 	int ret;
 
-	if (WARN_ON(!encoder))
+	if (WARN_ON(!encoder) || WARN_ON(!msm_dsi) || WARN_ON(!dev))
 		return -EINVAL;
 
 	msm_dsi->dev = dev;
···
 
 	return 0;
 fail:
-	if (msm_dsi) {
-		/* bridge/connector are normally destroyed by drm: */
-		if (msm_dsi->bridge) {
-			msm_dsi_manager_bridge_destroy(msm_dsi->bridge);
-			msm_dsi->bridge = NULL;
-		}
-
-		/* don't destroy connector if we didn't make it */
-		if (msm_dsi->connector && !msm_dsi->external_bridge)
-			msm_dsi->connector->funcs->destroy(msm_dsi->connector);
-
-		msm_dsi->connector = NULL;
+	/* bridge/connector are normally destroyed by drm: */
+	if (msm_dsi->bridge) {
+		msm_dsi_manager_bridge_destroy(msm_dsi->bridge);
+		msm_dsi->bridge = NULL;
 	}
+
+	/* don't destroy connector if we didn't make it */
+	if (msm_dsi->connector && !msm_dsi->external_bridge)
+		msm_dsi->connector->funcs->destroy(msm_dsi->connector);
+
+	msm_dsi->connector = NULL;
 
 	return ret;
 }