arm64: dts: freescale: imx8mp-toradex-smarc: use generic gpio node name

Use generic node name for the SoM GPIO expander, following the
Devicetree Specification generic node names recommendation.

Signed-off-by: Francesco Dolcini <[email protected]>
Signed-off-by: Shawn Guo <[email protected]>

Author: dolcini

arch/arm64/boot/dts/freescale/imx8mp-toradex-smarc.dtsi

@@ -434,7 +434,7 @@
 	single-master;
 	status = "okay";
 
-	som_gpio_expander: gpio-expander@21 {
+	som_gpio_expander: gpio@21 {
 		compatible = "nxp,pcal6408";
 		reg = <0x21>;
 		pinctrl-names = "default";