cxgb4/iw_cxgb4: TOS support

This series provides support for iWARP applications to specify a TOS
value and have that map to a VLAN Priority for iw_cxgb4 iWARP connections.

In iw_cxgb4, when allocating an L2T entry, pass the skb_priority based
on the tos value in the cm_id. Also pass the correct tos value during
connection setup so the passive side gets the client's desired tos.
When sending the FLOWC work request to FW, if the egress device is
in a vlan, then use the vlan priority bits as the scheduling class.
This allows associating RDMA connections with scheduling classes to
provide traffic shaping per flow.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>