Rationalize license text on Linuxolator files

Many licenses on Linuxolator files contained small variations from the
standard FreeBSD license text. To avoid license proliferation switch to
the standard 2-clause FreeBSD license for those files where I have
permission from each of the listed copyright holders. Additional files
still waiting on permission from others are listed in review D14210.

Approved by: dchagin, rdivacky, sos
MFC after: 1 week
MFC with: r329370
Sponsored by: The FreeBSD Foundation