[PATCH] move remove_dquot_ref to dqout.c

Remove_dquot_ref can move to dqout.c instead of beeing in inode.c under
#ifdef CONFIG_QUOTA.  Also clean the resulting code up a tiny little bit by
testing sb->dq_op earlier - it's constant over a filesystems lifetime.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>