locking, x86, iommu: Annotate iommu->register_lock as raw

The iommu->register_lock can be taken in atomic context and therefore
must not be preempted on -rt - annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 9310c69..19728c4 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -311,7 +311,7 @@
 	u64		cap;
 	u64		ecap;
 	u32		gcmd; /* Holds TE, EAFL. Don't need SRTP, SFL, WBF */
-	spinlock_t	register_lock; /* protect register handling */
+	raw_spinlock_t	register_lock; /* protect register handling */
 	int		seq_id;	/* sequence id of the iommu */
 	int		agaw; /* agaw of this iommu */
 	int		msagaw; /* max sagaw of this iommu */