amdgpu/pm: Add new hwmgr API function "emit_clock_levels"

 Extend commit 7f36948c92b2 ("amdgpu/pm: Implement new API function "emit" that accepts buffer base and write offset")
   Add new hwmgr API function "emit_clock_levels"
   - add member emit_clock_levels to pp_hwmgr_func
   - Implemented pp_dpm_emit_clock_levels
   - add pp_dpm_emit_clock_levels to pp_dpm_funcs

Signed-off-by: Darren Powell <darren.powell@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>