This resulted in the use of polling mode when other approaches
(dma or interrupts) would have been more appropriate.

Happened for transfers longer than 477 bytes.
Reported-by: NNoralf Tronnes <noralf@tronnes.org>
Signed-off-by: NMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: NMark Brown <broonie@kernel.org>