bpf: tcp: Fix an error in the bpf_tcp_ca_kfunc_ids list

There is a typo in the bbr function, s/even/event/.
This patch fixes it.

Fixes: e78aea8b ("bpf: tcp: Put some tcp cong functions in allowlist for bpf-tcp-cc")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210329003213.2274210-1-kafai@fb.com