conf: Fix XML generation for smartcards

When formatting XML for smartcard device with mode=host, libvirt
generates invalid XML if the device has address info associated:

<smartcard mode='host' <address type='ccid' controller='0' slot='1'/>

src/conf/domain_conf.c

@@ -7058,6 +7058,7 @@ virDomainSmartcardDefFormat(virBufferPtr buf,
             virBufferAddLit(buf, "/>\n");
             return 0;
         }
+        virBufferAddLit(buf, ">\n");
         break;
 
     case VIR_DOMAIN_SMARTCARD_TYPE_HOST_CERTIFICATES: