Rate limit kernel UFS/FFS cylinder group check-hash error messages.

When a large file is deleted or a large number of files are deleted,
even a single cylinder group with a bad check hash can generate
thousands of check-hash warnings. As with other filesystem messages
such as out-of-space, print a maximum of one check-hash error per
second. Note the limit is per filesystem. If two filesystems have
cylinder group(s) with a bad check hash, each will print a maximum
of one check-hash error message per second.

MFC-after: 1 week
Sponsored-by: The FreeBSD Foundation