intel-iommu: Fix array overflow

Fix possible array overflow:

drivers/pci/intel-iommu.c: In function ¡dmar_get_fault_reason¢:
drivers/pci/intel-iommu.c:753: warning: array subscript is above array bounds
drivers/pci/intel-iommu.c: In function ¡iommu_page_fault¢:
drivers/pci/intel-iommu.c:753: warning: array subscript is above array bounds

Signed-off-by: Takashi Iwai <[e-mail]>
Cc: Mark Gross <[e-mail]>
Acked-by: "Keshavamurthy, Anil S" <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/pci/intel-iommu.c

···
 
 char *dmar_get_fault_reason(u8 fault_reason)
 {
-	if (fault_reason > MAX_FAULT_REASON_IDX)
-		return fault_reason_strings[MAX_FAULT_REASON_IDX];
+	if (fault_reason >= MAX_FAULT_REASON_IDX)
+		return fault_reason_strings[MAX_FAULT_REASON_IDX - 1];
 	else
 		return fault_reason_strings[fault_reason];
 }