drm/amdgpu: Fix the warning info when unload or remove amdgpu

drm/amdgpu: Fix the warning info when unload or remove amdgpu

Checking INVOKE_CMD  to fix the below warning info when
unload or remove amdgpu driver

[  319.489809] Call Trace:
[  319.489810]  <TASK>
[  319.489812]  psp_ta_unload+0x9a/0xd0 [amdgpu]
[  319.489926]  ? smu_smc_hw_cleanup+0x2f6/0x360 [amdgpu]
[  319.490072]  psp_hw_fini+0xea/0x170 [amdgpu]
[  319.490231]  amdgpu_device_fini_hw+0x2fc/0x413 [amdgpu]
[  319.490398]  ? blocking_notifier_chain_unregister+0x56/0xb0
[  319.490401]  amdgpu_driver_unload_kms+0x51/0x60 [amdgpu]
[  319.490493]  amdgpu_pci_remove+0x5a/0x140 [amdgpu]
[  319.490583]  ? __pm_runtime_resume+0x60/0x90
[  319.490586]  pci_device_remove+0x3b/0xb0
[  319.490588]  __device_release_driver+0x1a8/0x2a0
[  319.490591]  driver_detach+0xf3/0x140
[  319.490593]  bus_remove_driver+0x6c/0xf0
[  319.490595]  driver_unregister+0x31/0x60
[  319.490597]  pci_unregister_driver+0x40/0x90
[  319.490599]  amdgpu_exit+0x15/0x44e [amdgpu]

Signed-off-by: Ma Jun <Jun.Ma2@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>