On sparc64 obtain the initiator ID to be used for SPI HBAs from the

On sparc64 obtain the initiator ID to be used for SPI HBAs from the
Open Firmware device tree in order to match what the PROM built-in
driver uses. This is especially important when netbooting Fujitsu
Siemens PRIMEPOWER250 as in that case the built-in driver isn't used
and the port facts PortSCSIID defaults to 0, conflicting with the
disk at the same address.