MAINTAINERS: add myself as partial audio reviewer

Volunteering as reviewer for some of the audio backends; namely
ALSA, CoreAudio and JACK.

Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <E1mMVca-0005ZJ-Lo@lizzy.crudebyte.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

MAINTAINERS

@@ -2285,11 +2285,13 @@ F: qapi/audio.json
 
 ALSA Audio backend
 M: Gerd Hoffmann <kraxel@redhat.com>
+R: Christian Schoenebeck <qemu_oss@crudebyte.com>
 S: Odd Fixes
 F: audio/alsaaudio.c
 
 Core Audio framework backend
 M: Gerd Hoffmann <kraxel@redhat.com>
+R: Christian Schoenebeck <qemu_oss@crudebyte.com>
 S: Odd Fixes
 F: audio/coreaudio.c
 
@@ -2300,6 +2302,7 @@ F: audio/dsound*
 
 JACK Audio Connection Kit backend
 M: Gerd Hoffmann <kraxel@redhat.com>
+R: Christian Schoenebeck <qemu_oss@crudebyte.com>
 S: Odd Fixes
 F: audio/jackaudio.c