drm/amdgpu/vm: fix documentation for amdgpu_vm_bo_param

Add new parameters.

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>