uboot-imx

ARM: keystone2: Allow to build with all image formats

u-boot.bin is a copy of:
u-boot-fit-dtb.bin if CONFIG_FIT_EMBED is enabled,
u-boot-dtb.bin if CONFIG_OF_SEPARATE is enabled,
u-boot-nodtb.bin if DT is not enabled.
So, use u-boot.bin to to generate keystone images instead of
u-boot-dtb.bin

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>