libpcap: remove unrecognized canusb option

canusb has been removed since version 1.8.1 and
https://github.com/the-tcpdump-group/libpcap/commit/93ca5ff7030aaf1219e1de05ec89a68384bfc50b



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>