Input: ft6236 - change module license string to match copyright notice

The copyright/license notice says that the code is licensed under GPL v2
only (not GPL v2+), so let's use proper string in MODULE_LICENSE().

Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/touchscreen/ft6236.c

···
 MODULE_AUTHOR("Sean Cross <[e-mail]>");
 MODULE_AUTHOR("Noralf Trønnes <[e-mail]>");
 MODULE_DESCRIPTION("FocalTech FT6236 TouchScreen driver");
-MODULE_LICENSE("GPL");
+MODULE_LICENSE("GPL v2");