[ Upstream commit 09f662f9 ]

Return error number instead of 0 on failures.

Fixes: a1e8c136 ("PM / OPP: "opp-hz" is optional for power domains")
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>