util: Fix uninitalized variable to avoid garbage value.

This commit is similar with 692400f4. It fixes an uninitialized
variable to avoid garbage value. This case, returns 0 jiffies if an
error occurs with virNetDevBridgeGet.
Signed-off-by: NJulio Faracco <jcfaracco@gmail.com>

src/util/virnetdevbridge.c

@@ -713,7 +713,7 @@ int virNetDevBridgeGetSTPDelay(const char *brname,
                                int *delayms)
 {
     int ret = -1;
-    unsigned long val;
+    unsigned long val = 0;
 
     ret = virNetDevBridgeGet(brname, "forward_delay", &val);
     *delayms = JIFFIES_TO_MS(val);