cxgb4: collect egress and ingress SGE queue contexts

Use meminfo to identify the egress and ingress context regions and
fetch all valid contexts from those regions. Also flush all contexts
before attempting collection to prevent stale information.

Signed-off-by: Rahul Lakkireddy <rahul.lakkireddy@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>