ena: Switch driver owners from semihalf to amazon in man file
- Update ena.4 manual file to include amazon owner emails.
- State that the driver is developed by amazon but leave
that it was originally written by Semihalf, similarly to other
drivers in the /share/man/ directory of the FreeBSD source code.
- Advance year in copyright notice to 2022.
MFC after: 2 weeks
Sponsored by: Amazon, Inc.
(cherry picked from commit fb47286c38a5315bdd93389b0547b8ccccdc7327)