cpufreq: Allow dynamic switching with CPUFREQ_ETERNAL latency

With the recent updates, CPUFREQ_ETERNAL is only used by the drivers
which don't know their transition latency but want to use dynamic
switching.

Anyway, the routine cpufreq_policy_transition_delay_us() caps the value
of transition latency to 10 ms now and that can be used safely with such
platforms.

Remove the check from cpufreq_init_governor() and allow dynamic
switching for such configurations as well.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>