MAINTAINERS: Include sof headers under ASoC

Add missing sof header files for ASoC.

Suggested-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/lkml/f258a7e6-0728-4f55-a71a-6e99113ce7e5@sirena.org.uk


Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20231005025618.work.355-kees@kernel.org


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