usb: gadget: Compilation warning fix

A compilation warning was added by the patch
"usb: gadget: use config_ep_by_speed() instead of ep_choose()".
This patch fixed it.

Signed-off-by: Tatyana Brokhman <tlinder@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>