ASoC: cs42l51: Fix mask for REVID

The REVID mask was changed by commit a1253ef6
"ASoC: cs42l51: split i2c from codec driver". Fix it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Brian Austin <brian.austin@cirrus.com>
Signed-off-by: Mark Brown <broonie@linaro.org>