Inject expected results for IBM Power when testing bus

There's no support for ide in IBM Power, and this test is
failing when it's being running in Power.
This patch inject the expected value in
test_xml_disk_bus_ide_and_virtio and
test_xml_disk_bus_ide when it's tested in Power
platform, so, when architecture is Power, the injected value
replace the ide by scsi.

Change-Id: I2db1ade0e049c3471989b121b9497bc5124ea567
Merge "Inject expected results for IBM Power when testing bus"