[PATCH] powerpc: convert macio_asic to use prom_parse

Converts the macio_asic core to use the new OF parsing routines instead
of relying on the pre-parsed values in struct device_node.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>