staging: vt6656: Fix URB submitted while active warning.

This error happens because PIPEnsControlOut and PIPEnsControlIn unlock the
spin lock for delay, letting in another thread.

The patch moves the current MP_SET_FLAG to before filling
of sUsbCtlRequest for pControlURB and clears it in event of failing.

Any thread calling either function while fMP_CONTROL_READS or fMP_CONTROL_WRITES
flags set will return STATUS_FAILURE.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Cc: stable@vger.kernel.org # 3.8
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>