amdgpu/pm: Powerplay API for smu , changed 4 dpm functions to use API

v2: fix errors and warnings flagged by checkpatch
v3: Context mismatch with revision v3 to patch 0003

New Functions
  smu_get_mclk        - implementation of the Powerplay API function get_mclk
  smu_get_sclk        - implementation of the Powerplay API function get_sclk
  smu_handle_dpm_task - implementation of the Powerplay API function dispatch_tasks

Modified Functions
  smu_dpm_set_power_gate - - modifed arg0 to match Powerplay API set_powergating_by_smu

Other Changes
  removed special smu handling in dpm functions and called through Powerplay API
  call to smu_dpm_set_power_gate via Powerplay API now locks mutex for UVD and VCE

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