H4 has two peripheral ports, one for "download" and one for OTG.
The one to use is selected through Kconfig.

NOTE:  not yet working; I suspect there's a clock still turned off
or something like that, since neither port responds.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>