drm/amdgpu: Use mmu_interval_insert instead of hmm_mirror

Remove the interval tree in the driver and rely on the tree maintained by
the mmu_notifier for delivering mmu_notifier invalidation callbacks.

For some reason amdgpu has a very complicated arrangement where it tries
to prevent duplicate entries in the interval_tree, this is not necessary,
each amdgpu_bo can be its own stand alone entry. interval_tree already
allows duplicates and overlaps in the tree.

Also, there is no need to remove entries upon a release callback, the
mmu_interval API safely allows objects to remain registered beyond the
lifetime of the mm. The driver only has to stop touching the pages during
release.

Link: https://lore.kernel.org/r/20191112202231.3856-12-jgg@ziepe.ca
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Tested-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

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

@@ -2633,6 +2633,7 @@ int amdgpu_device_init(struct amdgpu_device *adev,
 	mutex_init(&adev->virt.vf_errors.lock);
 	hash_init(adev->mn_hash);
 	mutex_init(&adev->lock_reset);
+	mutex_init(&adev->notifier_lock);
 	mutex_init(&adev->virt.dpm_mutex);
 	mutex_init(&adev->psp.mutex);