Move locking of a mark list into fsnotify_find_mark(). This reduces code
churn in the following patch changing lock protecting the list.
Reviewed-by: NMiklos Szeredi <mszeredi@redhat.com>
Reviewed-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NJan Kara <jack@suse.cz>