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/sysdev/fsl_msi.c b/arch/powerpc/sysdev/fsl_msi.c
index 62e5025..c6e11b0 100644
--- a/arch/powerpc/sysdev/fsl_msi.c
+++ b/arch/powerpc/sysdev/fsl_msi.c
@@ -173,7 +173,7 @@
 	u32 intr_index;
 	u32 have_shift = 0;
 
-	spin_lock(&desc->lock);
+	raw_spin_lock(&desc->lock);
 	if ((msi_data->feature &  FSL_PIC_IP_MASK) == FSL_PIC_IP_IPIC) {
 		if (desc->chip->mask_ack)
 			desc->chip->mask_ack(irq);
@@ -225,7 +225,7 @@
 		break;
 	}
 unlock:
-	spin_unlock(&desc->lock);
+	raw_spin_unlock(&desc->lock);
 }
 
 static int __devinit fsl_of_msi_probe(struct of_device *dev,