linux-firmware: Add a new FW 7.0.20.0

- Add a separate directory for the bnx2x FW.
 - Post a new FW version: 7.0.20.0

Signed-off-by: Vladislav Zolotarov <vladz@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

WHENCE

@@ -997,6 +997,9 @@ File: bnx2x-e1-5.2.7.0.fw
 File: bnx2x-e1h-5.2.7.0.fw
 File: bnx2x-e1-5.2.13.0.fw
 File: bnx2x-e1h-5.2.13.0.fw
+File: bnx2x/bnx2x-e2-7.0.20.0.fw
+File: bnx2x/bnx2x-e1-7.0.20.0.fw
+File: bnx2x/bnx2x-e1h-7.0.20.0.fw
 
 License:
   Copyright (c) 2007-2010 Broadcom Corporation