FreeBSD: Catch up with more VFS changes

Unused thread argument was removed from NDINIT*

https://cgit.freebsd.org/src/commit?id=7e1d3eefd410ca0fbae5a217422821244c3eeee4

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Ryan Moeller <freqlabs@FreeBSD.org>
Closes #12828