pnv/phb3: Add missing break statement

We obviously don't want to print out an error message if addr points to
a valid register.

Reported-by: Coverity CID 1419391 Missing break in switch
Fixes: 9ae1329ee2fe "ppc/pnv: Add models for POWER8 PHB3 PCIe Host bridge"
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <158153365202.3229002.11521084761048102466.stgit@bahia.lan>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/pci-host/pnv_phb3_pbcq.c

@@ -173,6 +173,7 @@ static void pnv_pbcq_pci_xscom_write(void *opaque, hwaddr addr,
     case PBCQ_PCI_BAR2:
         pbcq->pci_regs[reg] = val & 0xfffffffffc000000ull;
         pnv_pbcq_update_map(pbcq);
+        break;
     default:
         phb3_pbcq_error(pbcq, "%s @0x%"HWADDR_PRIx"=%"PRIx64, __func__,
                         addr, val);