drm/amdgpu: Fix kernel NULL pointer dereference in dpm functions

caused by
'commit 83e3c4615872 ("drm/amdgpu: Remove wrapper layer of smu ip functions")'

BUG: unable to handle kernel NULL pointer dereference at 00000000000005d8
[  313.241459] IP: ci_dpm_read_sensor+0x37/0xf0 [amdgpu]
Reviewed-by: Alex Deucher <alexander.deucher@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/ci_dpm.c

@@ -6244,6 +6244,7 @@ static int ci_dpm_early_init(void *handle)
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
 	adev->powerplay.pp_funcs = &ci_dpm_funcs;
+	adev->powerplay.pp_handle = adev;
 	ci_dpm_set_irq_funcs(adev);
 
 	return 0;

drivers/gpu/drm/amd/amdgpu/kv_dpm.c

@@ -2963,6 +2963,7 @@ static int kv_dpm_early_init(void *handle)
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
 	adev->powerplay.pp_funcs = &kv_dpm_funcs;
+	adev->powerplay.pp_handle = adev;
 	kv_dpm_set_irq_funcs(adev);
 
 	return 0;

drivers/gpu/drm/amd/amdgpu/si_dpm.c

@@ -7917,6 +7917,7 @@ static int si_dpm_early_init(void *handle)
 	struct amdgpu_device *adev = (struct amdgpu_device *)handle;
 
 	adev->powerplay.pp_funcs = &si_dpm_funcs;
+	adev->powerplay.pp_handle = adev;
 	si_dpm_set_irq_funcs(adev);
 	return 0;
 }