cpufreq: dt: Print error on failing to mark OPPs as shared

We need to explicitly mark OPPs as shared, when they are not defined
with OPP-v2 bindings. This operation can potentially fail, and in that
case we should at least print an error message.

Fixes: 2e02d872

 ("cpufreq: dt: Add support for operating-points-v2 bindings")
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>