[ Upstream commit 5674a92ca4b7e5a6a19231edd10298d30324cd27 ]

We forgot to set "err" on this error path.

Fixes: 1a2d397a ("gpio/powerpc: Eliminate duplication of of_get_named_gpio_flags()")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NLi Yang <leoyang.li@nxp.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>