of14: Add port desc optical property

This may be used in port stats and port status messages

Signed-off-by: Simon Horman <horms@verge.net.au>
of14: Add optical property to port status unit test

Signed-off-by: Simon Horman <horms@verge.net.au>
of14: Add optical property to port desc reply unit test

Signed-off-by: Simon Horman <horms@verge.net.au>
of13: Add port desc experimenter property

This may be used in port stats and port status messages

Signed-off-by: Simon Horman <horms@verge.net.au>
of14: Add experimenter property to port status unit test

Signed-off-by: Simon Horman <horms@verge.net.au>
of14: Add experimenter property to port desc reply unit test

Signed-off-by: Simon Horman <horms@verge.net.au>