ASoC: hdmi-codec: Add SNDRV_PCM_FMTBIT_32_LE playback format

The new playback format is needed for tda998x HDMI audio support. At
the moment the only other user of this codec is omap-hdmi-audio. This
change should not break anything because omap-hdmi-audio-dai, the
cpu-dai of omap-hdmi-audio, enforces sufficient constraints to
available sample formats.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>