When the -machine pseries,max-cpu-compat=X is supported use
machine parameter instead of -cpu host,compat=X parameter as
that is deprecated now with qemu >= v2.10.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1519146Signed-off-by: NShivaprasad G Bhat <sbhat@linux.vnet.ibm.com>
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>