ARM: msm: Add msm8660-surf.dts to Makefile.boot

Add this entry to the Makefile so that we can build the dtb
automatically with 'make dtbs'.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NDavid Brown <davidb@codeaurora.org>

arch/arm/mach-msm/Makefile.boot

   zreladdr-y		+= 0x10008000
 params_phys-y		:= 0x10000100
 initrd_phys-y		:= 0x10800000
+
+dtb-$(CONFIG_ARCH_MSM8X60) += msm8660-surf.dtb