ASoC: dt-bindings: fsl_rpmsg: Add compatible string for i.MX93

Add compatible string for i.MX93 platform which supports audio
function through rpmsg channel between Cortex-A and Cortex-M core.

Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230714092913.1591195-2-chancel.liu@nxp.com


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