UPSTREAM: af_unix: Replace BUG_ON() with WARN_ON_ONCE().

commit d0f6dc26 upstream.

This is a prep patch for the last patch in this series so that
checkpatch will not warn about BUG_ON().

Bug: 404256079
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20240129190435.57228-2-kuniyu@amazon.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 36f1f6ac)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I24f71464f1b5a500c0c5de6cc427c803896ca18f