drm/radeon: Add ATC VMID<-->PASID functions to kfd->kgd

This patch adds three new interfaces to kfd2kgd interface file of radeon.

The interfaces are:

- Check if a specific VMID has a valid PASID mapping
- Retrieve the PASID which is mapped to a specific VMID
- Issue a VMID invalidation request to the ATC

Signed-off-by: Alexey Skidanov <Alexey.Skidanov@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>