USB: missing usb_put_hcd to ohci-at91

Looks like usb_put_hcd was missing. Also, make an always-zero function
return void.

Signed-off-by: Pete Zaitcev <zaitcev@yahoo.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>