cxgb4vf: Revert force link up behaviour

Reverting force link up changes since this behaviour can be
achieved using VF link state feature.

Reverts:
commit 0913667a ("cxgb4vf: Forcefully link up virtual interfaces")

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Vishal Kulkarni <vishal@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>