clk: qcom: clk-cpu-osm: Refrain from using dummy clock ops for CPU cores

The callbacks in clk_dummy_ops dereference the clk_dummy pointer.
However, since the CPU core clocks have been modelled as clk_osm
structures, this might lead to referring or setting incorrect
member variables. Replace clk_dummy_ops with a custom clk_ops_core
implementation.

Change-Id: Id95b49c41724d0cd40325453ce20ef5d1a02409d
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>