core, engine: Prevent VM suspend in the ppc64 arch

This change prevents the suspension of VMs in architectures that do not
support it by checking the availability of this feature in the
canDoAction method of the HibernateVM command.

Change-Id: Ia0ccb0dd008319a2a230821415d902897690f01b
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1070189
Signed-off-by: Vitor de Lima <vitor.lima@eldorado.org.br>