ASoC: fsl_spdif: add support for enabling raw capture mode

Since i.MX8MM SPDIF interface is able to capture raw data.
Add support in SPDIF driver for this functionality.

Signed-off-by: Viorel Suman <viorel.suman@nxp.com>
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1619425444-8666-1-git-send-email-shengjiu.wang@nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>