[ALSA] Update MAINTAINERS for ALSA SoC

Add myself as a point of contact for the ALSA SoC subsystem and add a
reference to the development GIT tree.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lg@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

MAINTAINERS

@@ -3571,6 +3571,9 @@ S:	Maintained
 SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEMENT
 P:	Liam Girdwood
 M:	liam.girdwood@wolfsonmicro.com
+P:	Mark Brown
+M:	broonie@opensource.wolfsonmicro.com
+T:	git opensource.wolfsonmicro.com/linux-2.6-asoc
 L:	alsa-devel@alsa-project.org (subscribers-only)
 S:	Supported