drm: fix tainted kernel caused by drm_panel_orientation_quirks.c

drm_panel_orientation_quirks.c introduced in commit 404d1a3edc38 ("drm:
Add panel orientation quirks, v6.") taints the kernel when compiled as a
module. Fix this by adding MODULE_LICENSE().

Signed-off-by: David Lechner <david@lechnology.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1513881979-13801-1-git-send-email-david@lechnology.com

drivers/gpu/drm/drm_panel_orientation_quirks.c

@@ -9,6 +9,7 @@
  */
 
 #include <linux/dmi.h>
+#include <linux/module.h>
 #include <drm/drm_connector.h>
 
 #ifdef CONFIG_DMI
@@ -172,3 +173,5 @@ int drm_get_panel_orientation_quirk(int width, int height)
 EXPORT_SYMBOL(drm_get_panel_orientation_quirk);
 
 #endif
+
+MODULE_LICENSE("Dual MIT/GPL");