MAINTAINERS: 9p: add Christian Schoenebeck as reviewer

Volunteering as reviewer for 9p patches. As I am quite familiar with the
9p code base in the Linux kernel already, plus being current maintainer
of 9p in QEMU this move probably makes sense.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Christian Schoenebeck <[email protected]>
[Dominique: reworded description]
Signed-off-by: Dominique Martinet <[email protected]>

Author: cschoenebeck

MAINTAINERS

@@ -226,6 +226,7 @@ F:	drivers/net/ethernet/8390/
 M:	Eric Van Hensbergen <[email protected]>
 M:	Latchesar Ionkov <[email protected]>
 M:	Dominique Martinet <[email protected]>
+R:	Christian Schoenebeck <[email protected]>
 L:	[email protected]
 S:	Maintained
 W:	http://swik.net/v9fs