[ticket/11103] Remove unnecessary comments

Comments that are not needed because the actions are completely
self-explanatory

PHPBB3-11103

phpBB/includes/mcp/mcp_pm_reports.php

@@ -90,7 +90,6 @@ class mcp_pm_reports
 					trigger_error('NO_REPORT');
 				}
 
-				// Mark the notification as read
 				$phpbb_notifications->mark_notifications_read_by_parent('report_pm', $report_id, $user->data['user_id']);
 
 				$pm_id = $report['pm_id'];