usb: xhci: Add ROM loader for uPD720201

uPD720201 supports ROM and allows software to program the ROM and boot
from it. Add support for detecting if ROM is present, if so load the ROM
if not programmed earlier.

Signed-off-by: Vinod Koul <vkoul@kernel.org>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Christian Lamparter <chunkeey@googlemail.com>