ASoC: WM8903: Add of_match_table

This allows the device to be matched against the device tree using the
compatible flag directly, as is standard, rather than falling back to
matching .id_table against the non-vendor portion of the first compatible
property value.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>