ixgbe: Advance version to 4.2.1

With the addition of X550em_x SFP+ support, the driver is now
functionally equivalent to what will be the 4.2.1 driver when
released, so change the version to match.
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Krishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

@@ -79,7 +79,7 @@ char ixgbe_default_device_descr[] =
 static char ixgbe_default_device_descr[] =
 			      "Intel(R) 10 Gigabit Network Connection";
 #endif
-#define DRV_VERSION "4.0.1-k"
+#define DRV_VERSION "4.2.1-k"
 const char ixgbe_driver_version[] = DRV_VERSION;
 static const char ixgbe_copyright[] =
 				"Copyright (c) 1999-2015 Intel Corporation.";