subsys: usb: class: hid: Add OUT interrupt endpoint

patch add a OUT interrupt endpoint descriptor and registers a
corresponding notification callback with usb driver, which is invoked
when data is sent to device from host.

Implement the read ready notification as suggesteed by
Aurelien Jarno <aurelien@aurel32.net>

Signed-off-by: Savinay Dharmappa <savinay.dharmappa@intel.com>
Signed-off-by: Johann Fischer <j.fischer@phytec.de>