usb: gadget: f_hid: fix: Free out requests

commit 20d2ca95 upstream.

Requests for out endpoint are allocated in bind() function
but never released.

This commit ensures that all pending requests are released
when we disable out endpoint.

Fixes: 99c51500 ("usb: gadget: hidg: register OUT INT endpoint for SET_REPORT")
Tested-by: David Lechner <david@lechnology.com>
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>