pinctrl: single: fix refcount leak in pcs_add_gpio_func()

In the Linux kernel, the following vulnerability has been resolved: 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.