pmdomain: imx: gpcv2: fix an OF node reference leak in imx_gpcv2_probe()

imx_gpcv2_probe() leaks an OF node reference obtained by
of_get_child_by_name(). Fix it by declaring the device node with the
__free(device_node) cleanup construct.

This bug was found by an experimental static analysis tool that I am
developing.

Fixes: 03aa1262 ("soc: imx: Add GPCv2 power gating driver")
Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Cc: stable@vger.kernel.org
Message-ID: <20241215030159.1526624-1-joe@pf.is.s.u-tokyo.ac.jp>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>