pinctrl: add driver for MT8518

Add Pinctrl driver for MediaTek MT8518 SoC.

diff --git a/drivers/pinctrl/mediatek/Kconfig b/drivers/pinctrl/mediatek/Kconfig
index 9930ca1..22ee623 100644
--- a/drivers/pinctrl/mediatek/Kconfig
+++ b/drivers/pinctrl/mediatek/Kconfig
@@ -16,4 +16,8 @@
 	bool "MT8516 SoC pinctrl driver"
 	select PINCTRL_MTK
 
+config PINCTRL_MT8518
+        bool "MT8518 SoC pinctrl driver"
+	select PINCTRL_MTK
+
 endif