netsniff-ng: Rename protocol dissector member of struct pkt_buff
In commit
d312a25879d5 ("netsniff-ng nlmsg: Print netlink protocol
name"), the struct protocol member of struct pkt_buff was renamed to
handler to account for the newly added proto field. However, the
corresponding function pkt_set_proto wasn't renamed which is a bit
counter-intuitive. Fix this by renaming the member again, this time to
dissector (as I don't consider handler a particulary meaningful name)
and adjust the set function's name accordingly.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>