Once the module process a transfer in irq mode, the next poll transfer
will not work because the transmitter is left in inhibited state.

Fixes: 22417352 (Use polling mode on small transfers)
Reported-by: NEdward Kigwana <ekigwana@scires.com>
Signed-off-by: NRicardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: NMark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org