SPARC64: set active package and current instance to root device node before probe

Now that all PCI devices have been converted to new-device...finish-device we can
set both the active package and current instance to the root device node before
probe, giving all child devices a correct active package and instance chain during
creation.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>