USB: Add generic ULPI layer and a viewport

USB: Add generic ULPI layer and a viewport

Add partial ULPI specification implementation that should be enough to
interface the ULPI PHYs in the boot loader context.
Add a viewport implementation for Chipidea/ARC based controllers.

Signed-off-by: Jana Rapava <fermata7@gmail.com>
Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Cc: Remy Bohmer <linux@bohmer.net>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Wolfgang Grandegger <wg@denx.de>
Cc: Simon Glass <sjg@chromium.org>