inet: tcp: fix inetpeer_set_addr_v4()

David Ahern added a vif field in the a4 part of inetpeer_addr struct.

This broke IPv4 TCP fast open client side and more generally tcp metrics
cache, because inetpeer_addr_cmp() is now comparing two u32 instead of
one.

inetpeer_set_addr_v4() needs to properly init vif field, otherwise
the comparison result depends on uninitialized data.

Fixes: 192132b9 ("net: Add support for VRFs to inetpeer cache")
Reported-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>