We already changed NPU API for GPUs to not to call OPAL and the remaining
bit is initializing NPU structures.

This searches for POWER9 NVLinks attached to any device on a PHB and
initializes an NPU structure if any found.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>