power: reset: zx-reboot: put device node in zx_reboot_probe()

zx_reboot_probe() increments refcnt of zx296702-pcu device node by
of_find_compatible_node() and leaves it undecremented on both
successful and error paths.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Reviewed-by: Nicholas Mc Guire <der.herr@hofr.at>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>