pinctrl: st: Add of_node_put() before return

Each iteration of for_each_child_of_node puts the previous node, but in
the case of a return from the middle of the loop, there is no put, thus
causing a memory leak. Hence add an of_node_put before the return in
three places.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Linus Walleij <[e-mail]>

drivers/pinctrl/pinctrl-st.c

···
 		grp = &info->groups[*grp_index];
 		*grp_index += 1;
 		ret = st_pctl_dt_parse_groups(child, grp, info, i++);
-		if (ret)
+		if (ret) {
+			of_node_put(child);
 			return ret;
+		}
 	}
 	dev_info(info->dev, "Function[%d\t name:%s,\tgroups:%d]\n",
 				index, func->name, func->ngroups);
···
 		if (of_property_read_bool(child, "gpio-controller")) {
 			const char *bank_name = NULL;
 			ret = st_gpiolib_register_bank(info, bank, child);
-			if (ret)
+			if (ret) {
+				of_node_put(child);
 				return ret;
+			}
 
 			k = info->banks[bank].range.pin_base;
 			bank_name = info->banks[bank].range.name;
···
 							i++, &grp_index);
 			if (ret) {
 				dev_err(&pdev->dev, "No functions found.\n");
+				of_node_put(child);
 				return ret;
 			}
 		}