We should return if get_cpu_device() fails or it leads to a NULL
dereference.  Also dev_pm_opp_of_get_opp_desc_node() returns NULL on
error, it never returns error pointers.

Fixes: 46e2856b (cpufreq: Add Kryo CPU scaling driver)
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>