pinctrl: ralink: rt2880: return proper error code

Check for NULL shall return '-ENOMEM' instead of '-1'.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201213161721.6514-4-sergio.paracuellos@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/ralink/pinctrl-rt2880.c

@@ -206,7 +206,7 @@ static int rt2880_pinmux_index(struct rt2880_priv *p)
 	p->group_names = devm_kcalloc(p->dev, p->group_count,
 				      sizeof(char *), GFP_KERNEL);
 	if (!p->group_names)
-		return -1;
+		return -ENOMEM;
 
 	for (i = 0; i < p->group_count; i++) {
 		p->group_names[i] = p->groups[i].name;