cxgb4: Add support for T4 configuration file

Starting with T4 firmware version 1.3.11.0 the firmware now supports device
configuration via a Firmware Configuration File. The Firmware Configuration
File was primarily developed in order to centralize all of the configuration,
resource allocation, etc. for Unified Wire operation where multiple
Physical / Virtual Function Drivers would be using a T4 adapter simultaneously.

The Firmware Configuration file can live in three locations as shown below
in order of precedence.
1) User defined configuration file: /lib/firmware/cxgb4/t4-config.txt
2) Factory Default configuration file written to FLASH within
   the manufacturing process.
3) Hardwired driver configuration.

Signed-off-by: Jay Hernandez <jay@chelsio.com>
Signed-off-by: Vipul Pandya <vipul@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>