vz: always pass graphics address to sdk

We need this because apply graphics functions is used on
update too. Also in case of NULL address resolve it to default
instead of error.
Signed-off-by: NNikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>

src/vz/vz_sdk.c

@@ -2772,12 +2772,10 @@ static int prlsdkApplyGraphicsParams(PRL_HANDLE sdkdom,
         prlsdkCheckRetGoto(pret, cleanup);
     }
 
-    if ((glisten = virDomainGraphicsGetListen(gr, 0))) {
-        if (!glisten->address)
-            goto cleanup;
-        pret = PrlVmCfg_SetVNCHostName(sdkdom, glisten->address);
-        prlsdkCheckRetGoto(pret, cleanup);
-    }
+    glisten = virDomainGraphicsGetListen(gr, 0);
+    pret = PrlVmCfg_SetVNCHostName(sdkdom, glisten && glisten->address ?
+                                           glisten->address : "");
+    prlsdkCheckRetGoto(pret, cleanup);
 
     ret = 0;
  cleanup: