dtb: Add arch-vt8500 board files to arch/arm/boot/dts/Makefile

Add board files (vt8500-bv07, wm8505-ref and wm8650-mid)
to allow 'make dtbs' on arch-vt8500.

Signed-off-by: Tony Prisk <[e-mail]>
Signed-off-by: Olof Johansson <[e-mail]>

arch/arm/boot/dts/Makefile

···
 	vexpress-v2p-ca15-tc1.dtb \
 	vexpress-v2p-ca15_a7.dtb \
 	xenvm-4.2.dtb
+dtb-$(CONFIG_ARCH_VT8500) += vt8500-bv07.dtb \
+	wm8505-ref.dtb \
+	wm8650-mid.dtb
 
 endif