ASoC: imx-hdmi: Add support for HBR/HD bitstreaming

Enable HBR mode when the userspace sets 8 channel output with non-PCM
indicated in PCM status bits (AES0 & 0x02).

HBR mode allows passthrough/bitstreaming of TrueHD/DTS-HD encoded audio.

ALSA needs an appropriate imx-hdmi-soc.conf for most applications to
automatically set the AESx bits.

Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>