ASoC: Use a shared define for AC97 CODEC data formats

The AC97 wire format is completely fixed so CODECs don't have any choice
about the formats they accept but controllers accept a variety of data
formats and render them down onto the bus.  Have a shared define so all
the CODEC drivers will interoperate with any of our controller drivers.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>