USB: Add Intel Langwell USB Device Controller driver

Intel Langwell USB Device Controller is a High-Speed USB OTG device
controller in Intel Moorestown platform. It can work in OTG device mode
with Intel Langwell USB OTG transceiver driver as well as device-only
mode. The number of programmable endpoints is different through
controller revision.

NOTE:
This patch is the first version Intel Langwell USB OTG device controller
driver. The bug fixing is on going for some hardware and software
issues.  Intel Langwell USB OTG transceiver driver and EHCI driver
patches will be submitted later.

Supported features:
 - USB OTG protocol support with Intel Langwell USB OTG transceiver
   driver (turn on CONFIG_USB_LANGWELL_OTG)
 - Support control, bulk, interrupt and isochronous endpoints
   (isochronous not tested)
 - PCI D0/D3 power management support
 - Link Power Management (LPM) support

Tested gadget drivers:
 - g_file_storage
 - g_ether
 - g_zero

The passed tests:
 - g_file_storage: USBCV Chapter 9 tests
 - g_file_storage: USBCV MSC tests
 - g_file_storage: from/to host files copying
 - g_ether: ping, ftp and scp files from/to host
 - Hotplug, with and without hubs

Known issues:
 - g_ether: failed part of USBCV chap9 tests
 - LPM support not fully tested

TODO:
 - g_ether: pass all USBCV chap9 tests
 - g_zero: pass usbtest tests
 - Stress tests on different gadget drivers
 - On-chip private SRAM caching support

Signed-off-by: Xiaochen Shen <xiaochen.shen@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>