cxgb4: Adds a new Device Log Facility FW_DEVLOG_FACILITY_CF

The firmware team added a new Device Log Facility FW_DEVLOG_FACILITY_CF,
but the driver has been decoding Device Log messages with that Facility as
"(NULL)", fixing it.

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