cpufreq: Honour transition_latency over transition_delay_us

Some platforms like Arm's Juno can have a high transition latency that
can be larger than the 2ms cap introduced. If a driver reports
a transition_latency that is higher than the cap, then use it as-is.

Update comment s/10/2/ to reflect the new cap of 2ms.

Reported-by: Pierre Gondois <pierre.gondois@arm.com>
Signed-off-by: Qais Yousef <qyousef@layalina.io>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>