Retrieve from the firmware the DMA mask value we need to set according to
the device's PCI controller configuration. This is needed when working on
POWER9 machines, as the device's PCI controller is configured in a
different way in those machines.
Reviewed-by: Tomer Tayar <ttayar@habana.ai>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>