INPUT: sgi_btns: Add license specification

The SGI Volume Button interface driver uses GPL-only symbols
platform_driver_unregister and platform_driver_register, but
lacks license specification. Thus, when compiled as a module,
this driver cannot be installed. This patch fixes this by
adding the MODULE_LICENSE() specification.
Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.fi>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/input/misc/sgi_btns.c

@@ -174,5 +174,6 @@ static void __exit sgi_buttons_exit(void)
 	platform_driver_unregister(&sgi_buttons_driver);
 }
 
+MODULE_LICENSE("GPL");
 module_init(sgi_buttons_init);
 module_exit(sgi_buttons_exit);