xen: Fix determining when domain creation is complete

xen: Fix determining when domain creation is complete

d->creation_finished is used in several places alter behaviour depending on
whether the domain is being created, or is already running.

However, there is a latent bug if a toolstack component makes a pair of
pause/unpause calls, where creation will be considered finished prematurely.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Paul Durrant <paul.durrant@citrix.com>
master commit: 9d71e02e8420b5d4a48d92446a1edbff498ee1c6
master date: 2016-12-13 09:58:33 +0000