regulator: add check index of wm8350->pmic.pdev[]

Ensure that reg is within the bounds of array wm8350->pmic.pdev[].
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

drivers/regulator/wm8350-regulator.c

@@ -1419,6 +1419,8 @@ int wm8350_register_regulator(struct wm8350 *wm8350, int reg,
 {
 	struct platform_device *pdev;
 	int ret;
+	if (reg < 0 || reg >= NUM_WM8350_REGULATORS)
+		return -EINVAL;
 
 	if (wm8350->pmic.pdev[reg])
 		return -EBUSY;