ctladm.8: fix several errors in the "port" section

• Document the "-d" option.
• Add the "-c" and "-r" options to the summary.
• Correct the list of required options.
• Clarify that the "-t" option is only for use with "-o", "-w", and "-W"
• Replace references to the nonexistent "-n" with "-p".

Also, fix a few related error strings in the ctladm command.

MFC after: 2 weeks
Sponsored by: Axcient
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D45503