ARM: dts: imx: Add SoM compatible to i.MX8M Plus DHCOM PDK2

Add SoM compatible string into i.MX8MP DHCOM PDK2 compatible strings.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: uboot-imx <uboot-imx@nxp.com>
diff --git a/arch/arm/dts/imx8mp-dhcom-pdk2.dts b/arch/arm/dts/imx8mp-dhcom-pdk2.dts
index 0fcead3..c9a481a 100644
--- a/arch/arm/dts/imx8mp-dhcom-pdk2.dts
+++ b/arch/arm/dts/imx8mp-dhcom-pdk2.dts
@@ -16,7 +16,8 @@
 
 / {
 	model = "DH electronics i.MX8M Plus DHCOM Premium Developer Kit (2)";
-	compatible = "dh,imx8mp-dhcom-pdk2", "fsl,imx8mp";
+	compatible = "dh,imx8mp-dhcom-pdk2", "dh,imx8mp-dhcom-som",
+	             "fsl,imx8mp";
 
 	chosen {
 		stdout-path = &uart1;