[POWERPC] PS3: Fix system slowdown

The PS3 HV will deliver soft-disabled interrupts at the next HV call or
interrupt.  Add an HV call to local_irq_restore() to force the timely
delivery of any pending interrupts.

This fixes the system slowdown bug reported here
http://bugzilla.kernel.org/show_bug.cgi?id=8260



Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>