PM / OPP: Propagate error properly from dev_pm_opp_set_sharing_cpus()

We are returning 0 even in case of errors, fix it.

Fixes: 8d4d4e98 ("PM / OPP: Add helpers for initializing CPU OPPs")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.3 <stable@vger.kernel.org> # 4.3
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>