drivers: usb: Prevent from perpetual locked state

The USB CDC driver is unable to process any bulk IN transfers
after receiving spurious 'Clear Feature - Endpoint Halt' request
from host due to perpetual locked state caused by previously
scheduled transfer, that will never be finished, as the endpoint's state
is set to NAK. Fix by ignoring spurious request.

Signed-off-by: Piotr Ciura <piotr.ciura@hidglobal.com>