pinctrl: samsung: Constify samsung_pin_bank_type struct

This structure is not intended to be modified at runtime and functions
as constant data shared between multiple pin banks. This patch makes all
instances of it constant across the driver.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.h b/drivers/pinctrl/samsung/pinctrl-samsung.h
index da527b39..c677385 100644
--- a/drivers/pinctrl/samsung/pinctrl-samsung.h
+++ b/drivers/pinctrl/samsung/pinctrl-samsung.h
@@ -131,7 +131,7 @@
  * @pm_save: saved register values during suspend
  */
 struct samsung_pin_bank {
-	struct samsung_pin_bank_type *type;
+	const struct samsung_pin_bank_type *type;
 	u32		pctl_offset;
 	u32		pin_base;
 	u8		nr_pins;