ppc64: always use "unix" as serial device type

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
qcontainer: use bus "pci.0" on ppc64

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
fix qemu.unattended_install.cdrom on ppc64

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Merge pull request #1840 from giuseppe/giuseppe/ppc64

giuseppe/ppc64