drm/amdgpu: revert "use CPU for page table update if SDMA is unavailable"

That is clearly not something we should do upstream. The SDMA is
mandatory for the driver to work correctly.

We could do this for emulation and bringup, but in those cases the
engineer should probably enabled CPU based updates manually.

This reverts commit 62eefd10.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Yifan Zhang <yifan1.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2423,7 +2423,6 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
 int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 		   int32_t xcp_id)
 {
-	struct amdgpu_ip_block *ip_block;
 	struct amdgpu_bo *root_bo;
 	struct amdgpu_bo_vm *root;
 	int r, i;
@@ -2455,11 +2454,6 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	vm->use_cpu_for_update = !!(adev->vm_manager.vm_update_mode &
 				    AMDGPU_VM_USE_CPU_FOR_GFX);
 
-	/* use CPU for page table update if SDMA is unavailable */
-	ip_block = amdgpu_device_ip_get_ip_block(adev, AMD_IP_BLOCK_TYPE_SDMA);
-	if (!ip_block || ip_block->status.valid == false)
-		vm->use_cpu_for_update = true;
-
 	DRM_DEBUG_DRIVER("VM update mode is %s\n",
 			 vm->use_cpu_for_update ? "CPU" : "SDMA");
 	WARN_ONCE((vm->use_cpu_for_update &&