More descriptive content description for quick settings toggle.

Bug: 7362316
Change-Id: I7829402793e407e7ca483e1de2583df3b6c235bf

Author: caseyburkhardt

packages/SystemUI/res/layout/system_bar_notification_panel_title.xml

@@ -170,7 +170,7 @@
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
                     android:src="@drawable/ic_sysbar_quicksettings"
-                    android:contentDescription="@string/accessibility_settings_button"
+                    android:contentDescription="@string/accessibility_desc_quick_settings"
                     />
 
                 <ImageView