linux-phytec-fsl

spi: altera: Use bits_per_word_mask

This driver does not work for bits_per_word greater than 16.
Set bits_per_word_mask so spi core will reject transfers that attempt to use
an unsupported bits_per_word value.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@linaro.org>