drm/amdgpu: Fix oops when pp_funcs->switch_power_profile is unset

On Vega20 and other pre-production GPUs, powerplay is not enabled yet.
Check for NULL pointers before calling pp_funcs function pointers.

Also affects Kaveri.

CC: Joerg Roedel <jroedel@suse.de>
Signed-off-by: NFelix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Tested-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

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

@@ -501,8 +501,11 @@ void amdgpu_amdkfd_set_compute_idle(struct kgd_dev *kgd, bool idle)
 {
 	struct amdgpu_device *adev = (struct amdgpu_device *)kgd;
 
-	amdgpu_dpm_switch_power_profile(adev,
-					PP_SMC_POWER_PROFILE_COMPUTE, !idle);
+	if (adev->powerplay.pp_funcs &&
+	    adev->powerplay.pp_funcs->switch_power_profile)
+		amdgpu_dpm_switch_power_profile(adev,
+						PP_SMC_POWER_PROFILE_COMPUTE,
+						!idle);
 }
 
 bool amdgpu_amdkfd_is_kfd_vmid(struct amdgpu_device *adev, u32 vmid)