usb: gadget: Correct usb EP argument for BOT status request

This patch corrects the argument in usb_ep_free_request as it is
mistakenly set to ep_out. It should be ep_in for status request.

Signed-off-by: Manish Narani <mnarani@xilinx.com>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>