Now, the default kernel to boot the IGEP COM AQUILA is device tree based. As
old kernel is deprecated we should adapt the boot commands to use DTB files.

Also, with v3.9 and later of the Linux Kernel, uImage isn't builtable anymore
by default, so we should switch to use the bootz command.

Signed-off-by: Enric Balletbo i Serra <eballetbo@iseebcn.com>
Reviewed-by: Javier Martinez Canillas <javier@dowhile0.org>