usb: gadget: add Faraday fotg210_udc driver

Faraday fotg210 udc driver supports only Bulk transfer so far.
fotg210 could be configured as an USB2.0 peripheral.

This driver is tested with mass storage gadget driver on Faraday
EVB a369.

Signed-off-by: Yuan-Hsin Chen <yhchen@faraday-tech.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>