cxgb4: Fix for handling 1Gb/s SFP+ Transceiver Modules

We previously assumed that a Port's Capabilities and Advertised Capabilities
would never change from Port Initialization time.  This is no longer true
when we can have 10Gb/s and 1Gb/s SFP+ Transceiver Modules randomly swapped.

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