drm/amdgpu: TA unload messages are not actually sent to psp when amdgpu is uninstalled

V1:
  The psp_cmd_submit_buf function is called by psp_hw_fini to send
TA unload messages to psp to terminate ras, asd and tmr. But when
amdgpu is uninstalled, drm_dev_unplug is called earlier than
psp_hw_fini in amdgpu_pci_remove, the calling order as follows:
static void amdgpu_pci_remove(struct pci_dev *pdev) {
	drm_dev_unplug
	......
	amdgpu_driver_unload_kms->amdgpu_device_fini_hw->...
		->.hw_fini->psp_hw_fini->...
		->psp_ta_unload->psp_cmd_submit_buf
	......
}
The program will return when calling drm_dev_enter in psp_cmd_submit_buf.

So the call to drm_dev_enter in psp_cmd_submit_buf should be
removed, so that the TA unload messages can be sent to the psp
when amdgpu is uninstalled.

V2:
1. Restore psp_cmd_submit_buf to its original code.
2. Move drm_dev_unplug call after amdgpu_driver_unload_kms in
   amdgpu_pci_remove.
3. Since amdgpu_device_fini_hw is called by amdgpu_driver_unload_kms,
   remove the unplug check to release device mmio resource in
   amdgpu_device_fini_hw before calling drm_dev_unplug.
Signed-off-by: YiPeng Chai <YiPeng.Chai@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -3969,7 +3969,6 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
 
 	amdgpu_gart_dummy_page_fini(adev);
 
-	if (drm_dev_is_unplugged(adev_to_drm(adev)))
 	amdgpu_device_unmap_mmio(adev);
 
 }

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

@@ -2181,8 +2181,6 @@ amdgpu_pci_remove(struct pci_dev *pdev)
 	struct drm_device *dev = pci_get_drvdata(pdev);
 	struct amdgpu_device *adev = drm_to_adev(dev);
 
-	drm_dev_unplug(dev);
-
 	if (adev->pm.rpm_mode != AMDGPU_RUNPM_NONE) {
 		pm_runtime_get_sync(dev->dev);
 		pm_runtime_forbid(dev->dev);
@@ -2190,6 +2188,8 @@ amdgpu_pci_remove(struct pci_dev *pdev)
 
 	amdgpu_driver_unload_kms(dev);
 
+	drm_dev_unplug(dev);
+
 	/*
 	 * Flush any in flight DMA operations from device.
 	 * Clear the Bus Master Enable bit and then wait on the PCIe Device