inet_diag: change inet_diag_bc_sk() first argument

inet_diag: change inet_diag_bc_sk() first argument

We want to have access to the inet_diag_dump_data structure
in the following patch.

This patch removes duplication in callers.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250828102738.2065992-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>