cxgb4: do not fail vf instatiation in slave mode

We no longer require a check for cxgb4 to be MASTER
when configuring SRIOV, It was required when we had
module parameter to instantiate vf.

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>