Revert "xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM"
Revert "xen/spinlock: Disable IRQ spinlock (PV) allocation on PVHVM"

This reverts commit 70dd4998cb85f0ecd6ac892cc7232abefa432efb.

Now that the bugs have been resolved we can re-enable the
PV ticketlock implementation under PVHVM Xen guests.

Signed-off-by: Konrad Rzeszutek Wilk <da3a51b335cef0eb0e2c329c5ef6bcd6acef687a@oracle.com>
Reviewed-by: David Vrabel <b9d45bd1f671e508cd8daa63dfc3cabb597562df@citrix.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs