intel-ethernet: use correct module license

We recently updated all our SPDX identifiers to correctly
indicate our net/ethernet/intel/* drivers were always released
and intended to be released under GPL v2, but the MODULE_LICENSE
declaration was never updated.

Fix the MODULE_LICENSE to be GPL v2, for all our drivers.

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

drivers/net/ethernet/intel/igbvf/netdev.c

@@ -3011,7 +3011,7 @@ module_exit(igbvf_exit_module);
 
 MODULE_AUTHOR("Intel Corporation, <e1000-devel@lists.sourceforge.net>");
 MODULE_DESCRIPTION("Intel(R) Gigabit Virtual Function Network Driver");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");
 MODULE_VERSION(DRV_VERSION);
 
 /* netdev.c */