usb: gadget: Add full ep_matches() check past .match_ep() callback

usb: gadget: Add full ep_matches() check past .match_ep() callback

If .match_ep() callback returns non-NULL endpoint, immediately check
its usability and if the returned endpoint is usable, stop search and
return the endpoint. Otherwise, continue with best effort search for
usable endpoint.

Currently the code would attempt the best effort search in any case,
which may find another unexpected endpoint. It is likely that the
intention of the original code was to stop the search early.

Fixes: 77dcbdf3c1ce ("usb: gadget: Add match_ep() op to usb_gadget_ops")
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # on vim3
Link: https://lore.kernel.org/r/20240609213449.194762-5-marek.vasut+renesas@mailbox.org
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>