drm: bridge: adv7511: Support I2S IEC958 encoded PCM format

Support IEC958 encoded PCM format for ADV7511 so that ADV7511 HDMI
audio driver can accept the IEC958 data from the I2S input.

Signed-off-by: Sia Jee Heng <jee.heng.sia@intel.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210422064015.15285-1-jee.heng.sia@intel.com