sound/soc/sdw_utils/* missing from MAINTAINERS

[rfvirgil]

The code under sound/soc/sdw_utils/* was originally under sound/soc/intel/* so was included by the "INTEL ASoC DRIVERS" section of MAINTAINERS.

When the code was moved out to sound/soc/sdw_utils/* there wasn't an update to MAINTAINERS so that code now doesn't have any listed maintainer. get_maintainers shows only the top-level maintainers for all of sound/soc/* and sound/*