rtl_nic: add firmware rtl8125a-3

This adds firmware rtl8125a-3 for Realtek's 2.5Gbps chip RTL8125.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Chunhao Lin <hau@realtek.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

WHENCE

@@ -2908,6 +2908,9 @@ Version: 0.0.2
 File: rtl_nic/rtl8107e-2.fw
 Version: 0.0.2
 
+File: rtl_nic/rtl8125a-3.fw
+Version: 0.0.1
+
 Licence:
  * Copyright © 2011-2013, Realtek Semiconductor Corporation
  *