wlanstat(8): Rename from wlanstats(8) to keep consistency

[lwhsu]

Summary

wlanstat(8): Rename from wlanstats(8) to keep consistency

All the status and statistics utilties in base are ending with "stat",
the only exception is mailstats(8) but that's from sendmail.

Sponsored by:	The FreeBSD Foundation

Per discussion in the wireless monthly call and matrix group.

wlanstat(8): Follow-ups after moving to /usr/sbin and renaming

• Update related comments
• Remove from tools/tools/net80211

Sponsored by: The FreeBSD Foundation

[lwhsu]

misplaced.