selftests/bpf: Drop duplicate definition of i in test_sockmap

selftests/bpf: Drop duplicate definition of i in test_sockmap

There's already a definition of i in run_options() at the beginning, no
need to define a new one in "if (tx_prog_fd > 0)" block.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/8d690682330a59361562bca75d6903253d16f312.1716446893.git.tanggeliang@kylinos.cn