pinctrl: freescale: imx: Add of_node_put() before return

Each iteration of for_each_child_of_node() puts the previous node;
however, in the case of a return from the middle of the loop, there is no
put, thus causing a memory leak. Hence put of_node_put() statements as
required before two mid-loop return statements.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190808074720.15754-1-nishkadg.linux@gmail.com
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>