Move ep_matches() function to udc-core and rename it to
usb_gadget_ep_match_desc(). This function can be used by UDC drivers
in 'match_ep' callback to avoid writing lots of repetitive code.

Replace all calls of ep_matches() with usb_gadget_ep_match_desc().
Signed-off-by: NRobert Baldyga <r.baldyga@samsung.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>