livepatch: Wrong usage of spinlock on debug console.

livepatch: Wrong usage of spinlock on debug console.

If we have a large amount of livepatches and want to print them
on the console using 'xl debug-keys x' we eventually hit
the preemption check:

  if ( i && !(i % 64) )
  {
	spin_unlock(&payload_lock);
	process_pending_softirqs();
	if ( spin_trylock(&payload_lock) )
		return

<facepalm> The effect is that we have just effectively
taken the lock and returned without unlocking!

Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Reviewed-and-tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>