docs-networking: fix typo in define

The #define for NETIF_F_GSO_UDP_L4 was incorrect in the
documentation, fix it by making it match the actual code.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

Documentation/networking/netdev-features.txt

@@ -115,7 +115,7 @@ set, be it TCPv4 (when NETIF_F_TSO is enabled) or TCPv6 (NETIF_F_TSO6).
 
  * Transmit UDP segmentation offload
 
-NETIF_F_GSO_UDP_GSO_L4 accepts a single UDP header with a payload that exceeds
+NETIF_F_GSO_UDP_L4 accepts a single UDP header with a payload that exceeds
 gso_size. On segmentation, it segments the payload on gso_size boundaries and
 replicates the network and UDP headers (fixing up the last one if less than
 gso_size).