pinctrl: mediatek: add pinctrl-mtk-common-v2 module license

Kbuild warns when this file is built as a loadable module:

WARNING: modpost: missing MODULE_LICENSE() in drivers/pinctrl/mediatek/pinctrl-mtk-common-v2.o
see include/linux/module.h for more information

Add the missing license/author/description tags.

Fixes: 8174a8512e3e ("pinctrl: mediatek: make MediaTek pinctrl v2 driver ready for buidling loadable module")
Signed-off-by: Arnd Bergmann <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Linus Walleij <[e-mail]>

drivers/pinctrl/mediatek/pinctrl-mtk-common-v2.c

···
 	return 0;
 }
 EXPORT_SYMBOL_GPL(mtk_pinconf_adv_drive_get);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sean Wang <[e-mail]>");
+MODULE_DESCRIPTION("Pin configuration library module for mediatek SoCs");