Clock sources currently have support for asic specific
function pointers. But actual separation into functions
was never performed, leaving us with giant functions that
rely on switch.

This change creates separate functions, removing switch use.
Signed-off-by: NDmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Reviewed-by: NTony Cheng <Tony.Cheng@amd.com>
Acked-by: NLeo Li <sunpeng.li@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>