RDMA/cxgb4: Set the correct device physical function for iWARP connections

commit 94788657 upstream.

The PF passed to FW was 0, causing PCI failures in an SR-IOV environment.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>