tools: bpftool: drop unnecessary Author comments

Drop my author comments, those are from the early days of
bpftool and make little sense in tree, where we have quite
a few people contributing and git to attribute the work.

While at it bump some copyrights.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>