powerpc: mpc85xx: Add device tree support option for PBL boot image

The current Makefile always use u-boot.bin to generate
PBL boot image (u-boot.pbl), this patch changes it to
use u-boot-with-dtb.bin to support device tree when
CONFIG_OF_SEPARATE is enabled.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
1 file changed