passthrough/amd: Missing 'break'

Coverity CID 1055502

Signed-off-by: Tim Deegan <tim@xen.org>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

xen/drivers/passthrough/amd/iommu_guest.c

@@ -728,6 +728,7 @@ static void guest_iommu_mmio_write64(struct guest_iommu *iommu,
         break;
     case IOMMU_EVENT_LOG_BASE_LOW_OFFSET:
         u64_to_reg(&iommu->event_log.reg_base, val);
+        break;
     case IOMMU_PPR_LOG_BASE_LOW_OFFSET:
         u64_to_reg(&iommu->ppr_log.reg_base, val);
         break;