pinctrl: renesas: r8a7794: Add range checking to .pin_to_pocctrl()

The .pin_to_pocctrl() implementation for R-Car E2 does not perform a
full range check, unlike on all other SoCs.  Add the range check, so the
checker can validate better the consistency of the pin control tables.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/d23767ad7152327654192d7191f4b8ae19493966.1640269510.git.geert+renesas@glider.be

drivers/pinctrl/renesas/pfc-r8a7794.c

@@ -5623,6 +5623,9 @@ static const struct pinmux_cfg_reg pinmux_config_regs[] = {
 
 static int r8a7794_pin_to_pocctrl(struct sh_pfc *pfc, unsigned int pin, u32 *pocctrl)
 {
+	if (pin < RCAR_GP_PIN(6, 0) || pin > RCAR_GP_PIN(6, 23))
+		return -EINVAL;
+
 	*pocctrl = 0xe606006c;
 
 	switch (pin & 0x1f) {