Properly retrieve requests from pci_requests in consume_from_instance.
Without this the call to numa_fit_instance_to_host will fail because
it expects the request list.
And change the order in which apply_requests and numa_fit_instance_to_host
are called. Calling apply_requests first will remove devices from pools
and may make numa_fit_instance_to_host fail.
Change-Id: I41cf4e8e5c1dea5f91e5261a8f5e88f46c7994ef
Closes-bug: #1444021