FreeBSD: Add zfs_link_create() error handling

Originally Solaris didn't expect errors there, but they may happen
if we fail to add entry into ZAP.  Linux fixed it in #7421, but it
was never fully ported to FreeBSD.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored-By: iXsystems, Inc.
Closes #13215
Closes #16138

tests/test-runner/bin/zts-report.py.in

@@ -182,7 +182,6 @@ if sys.platform.startswith('freebsd'):
         'cli_root/zfs_unshare/zfs_unshare_008_pos': ['SKIP', na_reason],
         'cp_files/cp_files_002_pos': ['SKIP', na_reason],
         'link_count/link_count_001': ['SKIP', na_reason],
-        'casenorm/mixed_create_failure': ['FAIL', 13215],
         'mmap/mmap_sync_001_pos': ['SKIP', na_reason],
         'rsend/send_raw_ashift': ['SKIP', 14961],
     })