arm64: dts: renesas: beacon: Fix audio-1.8V pin enable

The fact the audio worked at all was a coincidence because the wrong
gpio enable was used.  Use the correct GPIO pin to ensure its operation.

Fixes: a1d8a344 ("arm64: dts: renesas: Introduce r8a774a1-beacon-rzg2m-kit")
Signed-off-by: Adam Ford <aford173@gmail.com>
Link: https://lore.kernel.org/r/20201213183759.223246-6-aford173@gmail.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/beacon-renesom-baseboard.dtsi

@@ -150,7 +150,7 @@ reg_audio: regulator_audio {
 		regulator-name = "audio-1.8V";
 		regulator-min-microvolt = <1800000>;
 		regulator-max-microvolt = <1800000>;
-		gpio = <&gpio_exp2 7 GPIO_ACTIVE_HIGH>;
+		gpio = <&gpio_exp4 1 GPIO_ACTIVE_HIGH>;
 		enable-active-high;
 	};