ANDROID: ARM: add config option to build zImage/dtb combo

Allows a defconfig to set a default dtb to concatenate with a zImage
to create a zImage-dtb.<dtb name>

Signed-off-by: Erik Gilling <konkers@android.com>
Change-Id: I34b643b1c49228fbae88a56e46c93c478089620d
2 files changed