powerpc: use IRQF_NO_DEBUG for IPIs

There is no need to use the lockup detector ("noirqdebug") for IPIs.
The ipistorm benchmark measures a ~10% improvement on high systems
when this flag is set.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210719130614.195886-1-clg@kaod.org