drm/loongson/7a2000: convert to struct drm_edid

Prefer the struct drm_edid based functions for reading the EDID and
updating the connector.
Reviewed-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Link: https://patchwork.freedesktop.org/patch/msgid/b8c477279a6ae1b44df72bee230180e277087fae.1715691257.git.jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/loongson/lsdc_output_7a2000.c

@@ -44,16 +44,15 @@
 
 static int ls7a2000_connector_get_modes(struct drm_connector *connector)
 {
-	unsigned int num = 0;
-	struct edid *edid;
+	int num;
 
 	if (connector->ddc) {
-		edid = drm_get_edid(connector, connector->ddc);
-		if (edid) {
-			drm_connector_update_edid_property(connector, edid);
-			num = drm_add_edid_modes(connector, edid);
-			kfree(edid);
-		}
+		const struct drm_edid *drm_edid;
+
+		drm_edid = drm_edid_read(connector);
+		drm_edid_connector_update(connector, drm_edid);
+		num = drm_edid_connector_add_modes(connector);
+		drm_edid_free(drm_edid);
 
 		return num;
 	}