board: sl28: add network variant 2 support

Although this variant has two external network ports, they are not (yet)
supported by the bootloader because they are connected via an internal
network switch. Otherwise its the same as the other variants.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 882ea02..918af8c 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -439,6 +439,7 @@
 	fsl-ls1012a-frwy.dtb
 dtb-$(CONFIG_TARGET_SL28) += fsl-ls1028a-kontron-sl28.dtb \
 	fsl-ls1028a-kontron-sl28-var1.dtb \
+	fsl-ls1028a-kontron-sl28-var2.dtb \
 	fsl-ls1028a-kontron-sl28-var3.dtb \
 	fsl-ls1028a-kontron-sl28-var4.dtb \