bitmap_daemon_work clears bits in the bitmap for blocks that haven't been
written to for a while.  It needs to be called regularly to make sure the
bitmap doesn't endup full of ones ....  but it wasn't.

So call it from the increasingly-inaptly-named md_check_recovery
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>