USB: WUSBCORE: clear RPIPE stall for control endpoints

When the HWA encounters a STALL on a control endpoint, it should clear the
RPIPE_STALL feature on the RPIPE before processing the next transfer
request.  Otherwise, all transfer requests on that endpoint after the
first STALL will fail because the RPIPE is still in the halted state.
This also removes the unneccessary call to spin_lock_irqsave for a nested
lock that was present in the first patch.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>