ASoC: google: dt-bindings: Add sc7280-herobrine machine bindings

Add devicetree bindings documentation file for sc7280 sound card
registration.

Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@quicinc.com>
Co-developed-by: Venkata Prasad Potturu <quic_potturu@quicinc.com>
Signed-off-by: Venkata Prasad Potturu <quic_potturu@quicinc.com>
Link: https://lore.kernel.org/r/1644497415-25291-2-git-send-email-quic_srivasam@quicinc.com
Signed-off-by: Mark Brown <broonie@kernel.org>