ARM: omap: add dtb targets

Makes it easier to just do 'make dtbs' for whatever the kernel was
configured for, just like some other platforms.
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NTony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/Makefile.boot

   zreladdr-y		+= 0x80008000
 params_phys-y		:= 0x80000100
 initrd_phys-y		:= 0x80800000
+
+dtb-$(CONFIG_SOC_OMAP2420)	+= omap2420-h4.dtb
+dtb-$(CONFIG_ARCH_OMAP3)	+= omap3-beagle.dtb omap3-evm.dtb
+dtb-$(CONFIG_ARCH_OMAP4)	+= omap4-panda.dtb omap4-pandaES.dtb
+dtb-$(CONFIG_ARCH_OMAP4)	+= omap4-var_som.dtb omap4-sdp.dtb
+dtb-$(CONFIG_SOC_OMAP5)		+= omap5-evm.dtb