virtio: allow starting with link down
virtio: allow starting with link down

Starting driver with link down should be ok, it is with every
other driver. So just allow it.

Signed-off-by: Stephen Hemminger <06fa905d7f2aaced6dc72e9511c71a2a51e8aead@networkplumber.org>
Signed-off-by: Changchun Ouyang <593bf1f161e79772915ea885e47cf0e95f4498c0@intel.com>
Acked-by: Huawei Xie <3b3be4428106761300a2ee559c9f71ecdb091553@intel.com>

phermansson/dpdk,phermansson/dpdk,phermansson/dpdk,phermansson/dpdk