selftests: net: tcp_mmap: clear whole tcp_zerocopy_receive struct

[ Upstream commit bf5525f3 ]

We added fields in tcp_zerocopy_receive structure,
so make sure to clear all fields to not pass garbage to the kernel.

We were lucky because recent additions added 'out' parameters,
still we need to clean our reference implementation, before folks
copy/paste it.

Fixes: c8856c05 ("tcp-zerocopy: Return inq along with tcp receive zerocopy.")
Fixes: 33946518

 ("tcp-zerocopy: Return sk_err (if set) along with tcp receive zerocopy.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>