[XFS] Update the MAINTAINERS file entry for XFS.

Remove David Chatterton from XFS entry in MAINTAINERS file.
Signed-off-by: Tim Shimmin <tes@sgi.com>

MAINTAINERS

@@ -4012,7 +4012,7 @@ S:	Supported
 
 XFS FILESYSTEM
 P:	Silicon Graphics Inc
-P:	Tim Shimmin, David Chatterton
+P:	Tim Shimmin
 M:	xfs-masters@oss.sgi.com
 L:	xfs@oss.sgi.com
 W:	http://oss.sgi.com/projects/xfs