cxgb4: Update Congestion Channel map for T6 adapter

Updating Congestion Channel/Priority Map in Congestion Manager Context
for T6. In T6 port 0 is mapped to channel 0 and port 1 is mapped to
channel 1. For 2 port T4/T5 adapter, port 0 is mapped to channel 0,1 and
port 1 is mapped to channel 2,3

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