ASoC: amd: acp: Add missing MODULE_DESCRIPTION in mach-common

ASoC: amd: acp: Add missing MODULE_DESCRIPTION in mach-common

Add a MODULE_DESCRIPTION() in the generic ACP machine driver to avoid
the following warning when building with W=1:

WARNING: modpost: missing MODULE_DESCRIPTION() in sound/soc/amd/acp/snd-acp-mach.o

Fixes: d4c750f2c7d4 ("ASoC: amd: acp: Add generic machine driver support for ACP cards")
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Link: https://msgid.link/r/20231209203229.878730-6-cristian.ciocaltea@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>