fsnotify: create a wrapper fsnotify_find_inode_mark()

In preparation to passing an object pointer to fsnotify_find_mark(), add
a wrapper fsnotify_find_inode_mark() and use it where possible.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240317184154.1200192-4-amir73il@gmail.com>