cmd: booti: fix invalid image address in debug message

With commit 6808ef9a ("move booti_setup to arch/arm/lig/image.c"),
images->ep has not been set at this point.

Fixes: 6808ef9a ("move booti_setup to arch/arm/lig/image.c")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Bin Chen <bin.chen@linaro.org>