USB: add Cypress c67x00 OTG controller core driver

This patch add the core driver for the c67x00 USB OTG controller.  The core
driver is responsible for the platform bus binding and creating either
USB HCD or USB Gadget instances for each of the serial interface engines
on the chip.

This driver does not directly implement the HCD or gadget behaviours; it
just controls access to the chip.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>