pinctrl: sunxi: Fix potential null pointer dereference

kzalloc can fail. Add a null check to avoid null pointer
dereference error while accessing the pointer later.

Signed-off-by: Sachin Kamat <[e-mail]>
Acked-by: Maxime Ripard <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/pinctrl/sunxi/pinctrl-sunxi.c

···
 			configlen++;
 
 		pinconfig = kzalloc(configlen * sizeof(*pinconfig), GFP_KERNEL);
+		if (!pinconfig) {
+			kfree(*map);
+			return -ENOMEM;
+		}
 
 		if (!of_property_read_u32(node, "allwinner,drive", &val)) {
 			u16 strength = (val + 1) * 10;