Add missing AC_MSG_RESULT(no) to configure

When the HAVE_IOPS_MKDIR_USERNS check fails output result
as required.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #13454