selftests/bpf: fix inet_csk_accept prototype in test_sk_storage_tracing.c

Recent kernel change ([0]) changed inet_csk_accept() prototype. Adapt
progs/test_sk_storage_tracing.c to take that into account.

  [0] 92ef0fd5 ("net: change proto and proto_ops accept type")

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240528223218.3445297-1-andrii@kernel.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>