Fix trivial calloc(3) arguments order
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <freqlabs@FreeBSD.org>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@gmail.com>
Closes #13052