cxgb4: Add support for T4 hardwired driver configuration settings

In case if user defined configuration file at /lib/firmware/cxgb4/t4-config.txt
location and also factory default configuration file written to FLASH are not
present then driver will use hardwired configuration settings.

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>