gpiolib: of: fix a memory leak in of_gpio_flags_quirks()

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

Cc: <stable@vger.kernel.org>
Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>