Use an array to multiplex by sockaddr->sa_family, this way adding new
families gets a bit easier and tidy.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-v3s85ra659tc40g1s1xaqoun@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>