net: vlan: avoid leaks on register_vlan_dev() failures

net: vlan: avoid leaks on register_vlan_dev() failures

VLAN checks for NETREG_UNINITIALIZED to distinguish between
registration failure and unregistration in progress.

Since commit 9682f0427247 ("net-sysfs: Fix reference count leak")
registration failure may, however, result in NETREG_UNREGISTERED
as well as NETREG_UNINITIALIZED.

This fix is similer to 4c9b76072bf5 ("rtnetlink: Fix
memory(net_device) leak when ->newlink fails")

Fixes: 9682f0427247 ("net-sysfs: Fix reference count leak")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>