clk: qcom: clk-cpu-osm: Add the fast_switch cpufreq callback

Implement and add the osm_cpufreq_fast_switch callback function
to allow CPU frequency switching from a scheduler context.

Change-Id: I6d3e365da97a93f69e5239b7d5a829568527c76f
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>