disp: msm: dsi: add indexing for panel timing nodes

The order of the panel timing nodes specified in the device tree is
not guaranteed to be the same while being parsed in the driver. This
results in unintended modes being set as preferred timing mode. The change
introduces cell-index property, so that the timing modes can be
accurately indexed and parsed.

Change-Id: I8ccd4d5a15643bfe72bc8be084f5e91fac26feb4
Signed-off-by: Satya Rama Aditya Pinapala <psraditya30@codeaurora.org>

msm/dsi/dsi_drm.c

@@ -970,8 +970,8 @@ int dsi_connector_get_modes(struct drm_connector *connector, void *data,
 			/* get the preferred mode from dsi display mode */
 			if (modes[i].is_preferred)
 				m->type |= DRM_MODE_TYPE_PREFERRED;
-		} else if (i == 0) {
-			/* set the first mode in list as preferred */
+		} else if (modes[i].mode_idx == 0) {
+			/* set the first mode in device tree list as preferred */
 			m->type |= DRM_MODE_TYPE_PREFERRED;
 		}
 		drm_mode_probed_add(connector, m);