genirq: Convert irq_desc.lock to raw_spinlock

Convert locks which cannot be sleeping locks in preempt-rt to
raw_spinlocks.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/powerpc/platforms/iseries/irq.c b/arch/powerpc/platforms/iseries/irq.c
index 0776225..86c4b29 100644
--- a/arch/powerpc/platforms/iseries/irq.c
+++ b/arch/powerpc/platforms/iseries/irq.c
@@ -217,9 +217,9 @@
 		struct irq_desc *desc = irq_to_desc(irq);
 
 		if (desc && desc->chip && desc->chip->startup) {
-			spin_lock_irqsave(&desc->lock, flags);
+			raw_spin_lock_irqsave(&desc->lock, flags);
 			desc->chip->startup(irq);
-			spin_unlock_irqrestore(&desc->lock, flags);
+			raw_spin_unlock_irqrestore(&desc->lock, flags);
 		}
 	}
 }