net: diag: support v4mapped sockets in inet_diag_find_one_icsk()

Lorenzo reported that we could not properly find v4mapped sockets
in inet_diag_find_one_icsk(). This patch fixes the issue.

[Cherry-pick of net 7c1306723ee916ea9f1fa7d9e4c7a6d029ca7aaf]

Reported-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Change-Id: I88ce179a5aec7800f8a100d9c80e6b63e1963219
Git-commit: 15d65ff63accb0fb58ec59b1d6fd9b1db8c25684
Git-repo: https://android.googlesource.com/kernel/common/


Signed-off-by: Ashwanth Goli <ashwanth@codeaurora.org>