vxlan: fix initialization with custom link parameters

Commit 0c867c9b ("vxlan: move Ethernet initialization to a separate
function") changed initialization order and as an unintended result, when the
user specifies additional link parameters (such as IFLA_ADDRESS) while
creating vxlan interface, those are overwritten by vxlan_ether_setup later.

It's necessary to call ether_setup from withing the ->setup callback. That
way, the correct parameters are set by rtnl_create_link later. This is done
also for VXLAN-GPE, as we don't know the interface type yet at that point,
and changed to the correct interface type later.

Fixes: 0c867c9b ("vxlan: move Ethernet initialization to a separate function")
Reported-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: Jiri Benc <jbenc@redhat.com>
Tested-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>