ipvlan: fix ipv6 outbound device

[ Upstream commit ca29fd7cce5a6444d57fb86517589a1a31c759e1 ]

When process the outbound packet of ipv6, we should assign the master
device to output device other than input device.

Signed-off-by: Keefe Liu <liuqifa@huawei.com>
Acked-by: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>