MAINTAINERS: add missing maintainers for Simple Audio Card

Mark Brown will take the patch. Add his name.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/87v7uqkpye.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: morimoto

MAINTAINERS

@@ -21991,6 +21991,7 @@ W:	https://github.com/thesofproject/linux/
 F:	sound/soc/sof/
 
 SOUND - GENERIC SOUND CARD (Simple-Audio-Card, Audio-Graph-Card)
+M:	Mark Brown <broonie@kernel.org>
 M:	Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
 S:	Supported
 L:	linux-sound@vger.kernel.org