USB: gadget: gadget zero uses new suspend/resume hooks

Use the new device-level suspend/resume hooks for Gadget Zero;
always enable them with the OTG test mode; and support remote
wakeup on both configurations even in non-OTG mode.

This ensures that both configurations can pass the USBCV remote
wakeup tests when the OTG test mode is enabled.  This changes
behavior by adding autoresume support to the loopback config
even in non-OTG mode; the test failure was that it didn't work
in OTG mode.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>