power/reset: Fix GPL v2 license string typo

Per license_is_gpl_compatible(), the MODULE_LICENSE() string for GPL v2 is
"GPL v2", not "GPLv2".  Use "GPL v2" so this module doesn't taint the
kernel.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/reset/restart-poweroff.c

@@ -62,5 +62,5 @@ module_platform_driver(restart_poweroff_driver);
 
 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
 MODULE_DESCRIPTION("restart poweroff driver");
-MODULE_LICENSE("GPLv2");
+MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:poweroff-restart");