arm: rmobile: alt: Add support USB and USB commands

This adds support for USB commands and USB storage device.

Signed-off-by: Yoshiyuki Ito <yoshiyuki.ito.ub@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>