Add support for ppc64le for guestperf.py. On ppc, console is usually
hvc0 and serial device for pseries machine is spapr-vty.

Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-Id: <20220809002451.91541-3-muriloo@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>