docs: networking: device drivers: convert freescale/gianfar.txt to ReST

- add SPDX header;
- adjust titles and chapters, adding proper markups;
- use :field: markup;
- add to networking/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/device_drivers/freescale/gianfar.txt → Documentation/networking/device_drivers/freescale/gianfar.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
 The Gianfar Ethernet Driver
+===========================
 
-Author: Andy Fleming <afleming@freescale.com>
-Updated: 2005-07-28
+:Author: Andy Fleming <afleming@freescale.com>
+:Updated: 2005-07-28
 
 
-CHECKSUM OFFLOADING
+Checksum Offloading
+===================
 
 The eTSEC controller (first included in parts from late 2005 like
 the 8548) has the ability to perform TCP, UDP, and IP checksums
@@ -15,13 +20,15 @@ packets.  Use ethtool to enable or disable this feature for RX
 and TX.
 
 VLAN
+====
 
 In order to use VLAN, please consult Linux documentation on
 configuring VLANs.  The gianfar driver supports hardware insertion and
 extraction of VLAN headers, but not filtering.  Filtering will be
 done by the kernel.
 
-MULTICASTING
+Multicasting
+============
 
 The gianfar driver supports using the group hash table on the
 TSEC (and the extended hash table on the eTSEC) for multicast
@@ -29,13 +36,15 @@ filtering.  On the eTSEC, the exact-match MAC registers are used
 before the hash tables.  See Linux documentation on how to join
 multicast groups.
 
-PADDING
+Padding
+=======
 
 The gianfar driver supports padding received frames with 2 bytes
 to align the IP header to a 16-byte boundary, when supported by
 hardware.
 
-ETHTOOL
+Ethtool
+=======
 
 The gianfar driver supports the use of ethtool for many
 configuration options.  You must run ethtool only on currently

Documentation/networking/device_drivers/index.rst

@@ -38,6 +38,7 @@ Contents:
    dec/dmfe
    dlink/dl2k
    freescale/dpaa
+   freescale/gianfar
 
 .. only::  subproject and html