mali_kbase: platform: Add GPU DVFS support and metrics

Adds support for clocking the GPU clocks according to a
DVFS table specified in the GPU's device tree entry using
a simple governor. Support also added for tracking GPU
power status along with time in state for each DVFS OPP.

Bug: 156057140
Bug: 158091247
Signed-off-by: Sidath Senanayake <sidaths@google.com>
Change-Id: I0b83336c24f0b724a26f4de6b97cf15d9687377b