dts/Makefile: Add build support for LS2080a QDS & RDB board DTS

This patch adds build support for LS2080a QDS & RDB board DTS files
in the arm64 DTS Makefile.
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@freescale.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/boot/dts/freescale/Makefile

+dtb-$(CONFIG_ARCH_LAYERSCAPE) += fsl-ls2080a-qds.dtb
+dtb-$(CONFIG_ARCH_LAYERSCAPE) += fsl-ls2080a-rdb.dtb
 dtb-$(CONFIG_ARCH_LAYERSCAPE) += fsl-ls2080a-simu.dtb
  
 always		:= $(dtb-y)