selftests/bpf: Honour the sotype of af_unix redir tests

Do actually test the sotype as specified by the caller.

This picks up after commit 75e0e27d ("selftest/bpf: Change udp to inet
in some function names").

Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://lore.kernel.org/r/20240731-selftest-sockmap-fixes-v2-4-08a0c73abed2@rbox.co


Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>