build: Add support for device tree in boot.img

Add support for optional device tree image (dt.img)
to boot and recovery images.  Some devices use kernel device
tree and this adds the device tree image as a section within
the boot/recovery images.

Change-Id: I91431ef2f4b86485895678916e39a8572be878eb

Conflicts:
	core/Makefile
1 file changed