usb: gadget: Add match_ep() op to usb_gadget_ops

Add match_ep() op to usb_gadget_ops similar to Linux kernel which is
useful in finding a suitable ep match for the function driver. This will
avoid adding more gadget_is_xxx() handling code to usb_ep_autoconfig().

Also sync usb_ep_caps struct thats is usually used in the match_ep()
callback by the gadget controller driver

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>