arm64: dts: mt6358: Add the compatible for the regulators

The regulators are expected to be instantiated with matching the
device-tree compatible, so add the proper compatible name under the
regulators node.

Signed-off-by: Enric Balletbo i Serra <[e-mail]>
Tested-by: Hsin-Yi Wang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Matthias Brugger <[e-mail]>

arch/arm64/boot/dts/mediatek/mt6358.dtsi

···
 		};
 
 		mt6358regulator: mt6358regulator {
+			compatible = "mediatek,mt6358-regulator";
+
 			mt6358_vdram1_reg: buck_vdram1 {
 				regulator-name = "vdram1";
 				regulator-min-microvolt = <500000>;