usb: gadget: hid: mirror init operations in module cleanup

So far platform driver has been unregistered first,
so just after that the usb composite is still available,
but there is no hid data any more.

Reverse the order so that first the usb composite becomes
unavailable and second the hid data goes away.

Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>