MIPS: xilfpga: Add xilfpga device tree files.

Add device tree files for the MIPSfpga platform.

See Documentation/devicetree/bindings/mips/img/xilfpga.txt
for details about MIPSfpga

Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
Cc: robh+dt@kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11362/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/boot/dts/xilfpga/Makefile

@@ -0,0 +1,9 @@
+dtb-$(CONFIG_XILFPGA_NEXYS4DDR)	+= nexys4ddr.dtb
+
+obj-y				+= $(patsubst %.dtb, %.dtb.o, $(dtb-y))
+
+# Force kbuild to make empty built-in.o if necessary
+obj-				+= dummy.o
+
+always				:= $(dtb-y)
+clean-files	:= *.dtb *.dtb.S