mali_kbase: platform: dvfs: Print clock changes to log

This change removes the reporting of GPU clock rate changes
via the non-standard clock_set_rate tracepoint and instead
prints the changes via GPU_LOG. This change will be followed
up with another change that reports these clock changes in a
standardized way that can be picked up by tools such as
AGI.

Bug: 169571973
Signed-off-by: Sidath Senanayake <sidaths@google.com>
Change-Id: I54517248661f4c9a501f0cd1ad476b931c7f2f2f