clk: qcom: clk-cpu-osm: Register cycle counter callbacks with scheduler

Implement the cycle counter callback function that returns
the running cycle counter value. This allows the scheduler
to estimate CPU frequency.

Change-Id: I309f0f1f0039d4b758ccc7c5c65b2efe832597cc
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>