pinctrl: falcon: add missing put_device() call in pinctrl_falcon_probe()

pinctrl: falcon: add missing put_device() call in pinctrl_falcon_probe()

if of_find_device_by_node() succeed, pinctrl_falcon_probe() doesn't have
a corresponding put_device(). Thus add put_device() to fix the exception
handling for this function implementation.

Fixes: ad092642cf98 ("OF: pinctrl: MIPS: lantiq: adds support for FALCON SoC")
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20201119011219.2248232-1-yukuai3@huawei.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>