drm/amdgpu: Remove wrapper layer of smu ip functions

1. delete amdgpu_powerplay.c used for wrapping smu ip functions
2. delete struct pp_instance,
3. make struct hwmgr as the smu hw handle.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/Makefile

@@ -87,8 +87,7 @@ amdgpu-y += \
 
 # add SMC block
 amdgpu-y += \
-	amdgpu_dpm.o \
-	amdgpu_powerplay.o
+	amdgpu_dpm.o
 
 # add DCE block
 amdgpu-y += \