ASoC: amd: vg: apply sample bits pcm constraint

ACP I2S controller has limitation to program different BCLK
for TX and RX paths.
Headset path uses I2S SP controller instance.
As per requirement, Restricted 32 bits as sample bits by
applying pcm constraint in startup calabck for Headset path.

Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@amd.com>
Link: https://lore.kernel.org/r/20220223071959.13539-5-Vijendar.Mukunda@amd.com


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