ARM: dts: omap3-gta04: add a comment how to reference the tca6507 gpio

Make clear how to use the wifi_reset since it is not obvious.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/omap3-gta04.dtsi

@@ -436,7 +436,7 @@ gta04_led4: green_power@4 {
 			reg = <0x4>;
 		};
 
-		wifi_reset: wifi_reset@6 {
+		wifi_reset: wifi_reset@6 { /* reference as <&tca_gpios 0 0> since it is currently the only GPIO */
 			reg = <0x6>;
 			compatible = "gpio";
 		};