MAINTAINERS: mark bcache as orphan

The submitted patches are not being reacted upon, and Jens is only picking
up stable fixes on an rather ad-hoc basis.

Link: lkml.kernel.org/r/574462C5.40307@kernel.dk
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

MAINTAINERS

@@ -2222,7 +2222,7 @@ BCACHE (BLOCK LAYER CACHE)
 M:	Kent Overstreet <kent.overstreet@gmail.com>
 L:	linux-bcache@vger.kernel.org
 W:	http://bcache.evilpiepirate.org
-S:	Maintained
+S:	Orphan
 F:	drivers/md/bcache/
 
 BDISP ST MEDIA DRIVER