amdgpu/pm: Powerplay API for smu , changed 5 dpm powergating & sensor functions to use API

v2: add comment to highlight assignment that changes uint32_t value to int
    fix errors flagged by checkpatch.pl

New Functions
  smu_get_baco_capability() - Implement Powerplay API get_asic_baco_capability
  smu_baco_set_state()      - Implement Powerplay API set_asic_baco_state

Modified Functions
  smu_read_sensor() - modifed signature to match Powerplay API read_sensor

Other Changes
  added 3 above smu Powerplay functions to swsmu_dpm_funcs
  removed special smu handling in 5 dpm functions and called through Powerplay API

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>