bpf: sockmap: Don't attach programs to UDP sockets

bpf: sockmap: Don't attach programs to UDP sockets

[ Upstream commit f6fede8569689dd31e7b0ed15024b25e5ce2e2e5 ]

The stream parser infrastructure isn't set up to deal with UDP
sockets, so we mustn't try to attach programs to them.

I remember making this change at some point, but I must have lost
it while rebasing or something similar.

Fixes: 7b98cd42b049 ("bpf: sockmap: Add UDP support")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20200611172520.327602-1-lmb@cloudflare.com
Signed-off-by: Sasha Levin <sashal@kernel.org>