ASoC: dt-bindings: atmel-classd: add sam9x7 compatible

Add sam9x7 compatible to DT bindings documentation.

Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Link: https://lore.kernel.org/r/20240223172608.672190-1-varshini.rajendran@microchip.com


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