cxgb4: Initialize RSS mode for all Ports

Implements t4_init_rss_mode() to initialize the rss_mode for all the ports. If
Tunnel All Lookup isn't specified in the global RSS Configuration, then we need
to specify a default Ingress Queue for any ingress packets which aren't hashed.
We'll use our first ingress queue.

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>