pinctrl: nomadik: Add missing of_node_put() in nmk_pinctrl_probe

This node pointer is returned by of_parse_phandle() with refcount
incremented in this function. Calling of_node_put() to avoid
the refcount leak.

Fixes: 32e67eee

 ("pinctrl: nomadik: Allow prcm_base to be extracted from Device Tree")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Link: https://lore.kernel.org/r/20220307115116.25316-1-linmq006@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>