commit b41583e7 upstream.

In case of 8 bit mode and DMA usage we end up with every second byte written as
0. We have to respect bits_per_word settings what this patch actually does.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>