MAINTAINERS: Add Shengjiu to maintainer list of sound/soc/fsl

Shengjiu has been actively working on latest FSL platforms and
keeping upstream effort as well, while I have been working on
other subsystem lately and cannot guarantee audio patch review
in the near term. So replacing with him in the maintainer list.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20220317041806.28230-1-nicoleotsuka@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>