If nova_virt_type variable is not defined in defaults/main.yml,
Using command "egrep -c '(vmx|svm)' /proc/cpuinfo" in
deploy environment, it can easily tell us what the right
virt_type is according to the return value.
If this command returns a value of one or greater, your
compute node supports hardware acceleration and just set
virt_type = kvm.
If this command returns a value of zero, your compute node
does not support hardware acceleration and you must configure
virt_type = qemu instead of kvm.
Change-Id: I6e36ffcb56d50556df0803aea9f4cd7850fada5a
989191607f