iommu/amd: Use BUG_ON instead of if () BUG()

Found by a coccicheck script.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index f7b875b..1131664 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -356,8 +356,8 @@
 		free_pasid_states_level2(dev_state->states);
 	else if (dev_state->pasid_levels == 1)
 		free_pasid_states_level1(dev_state->states);
-	else if (dev_state->pasid_levels != 0)
-		BUG();
+	else
+		BUG_ON(dev_state->pasid_levels != 0);
 
 	free_page((unsigned long)dev_state->states);
 }