Convert the WM8904 audio CODEC bindings to DT schema.

Compared to the original binding #sound-dai-cells and the missing power
supplies are added. The latter are all required as described in the
datasheet.

Datasheet: https://statics.cirrus.com/pubs/proDatasheet/WM8904_Rev4.1.pdfSigned-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230719121918.247397-1-francesco@dolcini.itSigned-off-by: Mark Brown <broonie@kernel.org>