xfs: set XFS_SICK_INO_SYMLINK_ZAPPED explicitly when zapping a symlink

If we need to reset a symlink target to the "durr it's busted" string,
then we clear the zapped flag as well.  However, this should be using
the provided helper so that we don't set the zapped state on an
otherwise ok symlink.

Cc: <stable@vger.kernel.org> # v6.10
Fixes: 2651923d ("xfs: online repair of symbolic links")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>