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>
diff --git a/drivers/regulator/wm8350-regulator.c b/drivers/regulator/wm8350-regulator.c
index 17a00b0..768bd0e 100644
--- a/drivers/regulator/wm8350-regulator.c
+++ b/drivers/regulator/wm8350-regulator.c
@@ -1419,6 +1419,8 @@
 {
 	struct platform_device *pdev;
 	int ret;
+	if (reg < 0 || reg >= NUM_WM8350_REGULATORS)
+		return -EINVAL;
 
 	if (wm8350->pmic.pdev[reg])
 		return -EBUSY;