pinctrl: single: check function mask to be non-zero

Otherwise it can generate a division by zero, which has an undefined
behavior.

Signed-off-by: Dario Binacchi <dariobin@libero.it>

drivers/pinctrl/pinctrl-single.c

@@ -335,6 +335,10 @@ static int single_configure_bits(struct udevice *dev,
 	phys_addr_t reg;
 	u32 offset, val, mask, bit_pos, val_pos, mask_pos, submask;
 
+	/* If function mask is null, needn't enable it. */
+	if (!pdata->mask)
+		return 0;
+
 	npins_in_reg = pdata->width / priv->bits_per_pin;
 	func = single_allocate_function(dev, count * npins_in_reg);
 	if (IS_ERR(func))
@@ -469,6 +473,11 @@ static int single_probe(struct udevice *dev)
 
 	priv->npins = size / (pdata->width / BITS_PER_BYTE);
 	if (pdata->bits_per_mux) {
+		if (!pdata->mask) {
+			dev_err(dev, "function mask needs to be non-zero\n");
+			return -EINVAL;
+		}
+
 		priv->bits_per_pin = fls(pdata->mask);
 		priv->npins *= (pdata->width / priv->bits_per_pin);
 	}