usb: gadget: epautoconf: remove ep and desc configuration from ep_matches()

As function ep_matches() is used to match endpoint with usb descriptor it's
highly unintuitive that it modifies endpoint and descriptor structures fields.
This patch moves code configuring ep and desc from ep_matches() to
usb_ep_autoconfig_ss(), so now function ep_matches() does nothing more than
its name suggests.

[ balbi@ti.com : fix build warning ]

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>