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

Add Shengjiu who's actively working on the latest fsl/nxp audio drivers.
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/20200707045829.10002-1-nicoleotsuka@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

MAINTAINERS

@@ -6876,6 +6876,7 @@ M:	Timur Tabi <timur@kernel.org>
 M:	Nicolin Chen <nicoleotsuka@gmail.com>
 M:	Xiubo Li <Xiubo.Lee@gmail.com>
 R:	Fabio Estevam <festevam@gmail.com>
+R:	Shengjiu Wang <shengjiu.wang@gmail.com>
 L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
 L:	linuxppc-dev@lists.ozlabs.org
 S:	Maintained