clk: msm: clock-osm: register cycle counter callbacks with scheduler

Implement clk_osm_get_cpu_cycle_counter() which returns the
running cycle counter value. Register these two functions with
a scheduler-provided callback to allow the scheduler to estimate
CPU frequency without notification. Lastly, setup the cycle
counter to be increased on every rising edge of the XO clock
for improved accuracy.

Change-Id: Ie0f60ca79efc05901a88da13f7a6476f390518a5
CRs-Fixed: 988356
Signed-off-by: Osvaldo Banuelos <osvaldob@codeaurora.org>