pinctrl: single: fix refcount leak in pcs_add_gpio_func()

pinctrl: single: fix refcount leak in pcs_add_gpio_func()

of_parse_phandle_with_args() returns a device_node pointer with refcount
incremented in gpiospec.np. The loop iterates through all phandles but
never releases the reference, causing a refcount leak on each iteration.

Add of_node_put() calls to release the reference after extracting the
needed arguments and on the error path when devm_kzalloc() fails.

This bug was detected by our static analysis tool and verified by my
code review.

Fixes: a1a277eb76b3 ("pinctrl: single: create new gpio function range")
Signed-off-by: Wei Li <unsw.weili@gmail.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>