arm64: dts: uniphier: add specific compatible to SoC-Glue node

This is a simple MFD, but add a specific compatible just in case.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm64/boot/dts/socionext/uniphier-ld20.dtsi

@@ -290,7 +290,8 @@ peri_rst: reset {
 		};
 
 		soc-glue@5f800000 {
-			compatible = "simple-mfd", "syscon";
+			compatible = "socionext,uniphier-soc-glue",
+				     "simple-mfd", "syscon";
 			reg = <0x5f800000 0x2000>;
 
 			pinctrl: pinctrl {