pinctrl: add driver for MT8518

Add Pinctrl driver for MediaTek MT8518 SoC.

diff --git a/drivers/pinctrl/mediatek/Makefile b/drivers/pinctrl/mediatek/Makefile
index c4f2908..0ab7b15 100644
--- a/drivers/pinctrl/mediatek/Makefile
+++ b/drivers/pinctrl/mediatek/Makefile
@@ -6,3 +6,4 @@
 obj-$(CONFIG_PINCTRL_MT7623) += pinctrl-mt7623.o
 obj-$(CONFIG_PINCTRL_MT7629) += pinctrl-mt7629.o
 obj-$(CONFIG_PINCTRL_MT8516) += pinctrl-mt8516.o
+obj-$(CONFIG_PINCTRL_MT8518) += pinctrl-mt8518.o