mlx4_core: INIT/CLOSE port logic for IB ports in SR-IOV mode

Normally, INIT_PORT and CLOSE_PORT are invoked when special QP0
transitions to RTR, or transitions to ERR/RESET respectively.

In SR-IOV mode, however, the master is also paravirtualized.  This in
turn requires that we not do INIT_PORT until the entire QP0 path (real
QP0 and proxy QP0) is ready to receive.  When the real QP0 goes down,
we should indicate that the port is not active.

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Roland Dreier <roland@purestorage.com>