netmap: fix coverity warning 1362789

** CID 1362789:  Null pointer dereferences  (FORWARD_NULL)
/src/runmode-netmap.c: 247 in ParseNetmapConfig()

________________________________________________________________________________________________________
*** CID 1362789:  Null pointer dereferences  (FORWARD_NULL)
/src/runmode-netmap.c: 247 in ParseNetmapConfig()
241         strlcpy(aconf->iface_name, iface_name, sizeof(aconf->iface_name));
242         SC_ATOMIC_INIT(aconf->ref);
243         (void) SC_ATOMIC_ADD(aconf->ref, 1);
244
245         /* Find initial node */
246         netmap_node = ConfGetNode("netmap");
>>>     CID 1362789:  Null pointer dereferences  (FORWARD_NULL)
>>>     Comparing "netmap_node" to null implies that "netmap_node" might be null.
247         if (netmap_node == NULL) {
248             SCLogInfo("Unable to find netmap config using default value");
249         } else {
250             if_root = ConfFindDeviceConfig(netmap_node, aconf->iface_name);
251             if_default = ConfFindDeviceConfig(netmap_node, "default");
252         }

src/runmode-netmap.c

@@ -255,10 +255,12 @@ static void *ParseNetmapConfig(const char *iface_name)
     ParseNetmapSettings(&aconf->in, aconf->iface_name, if_root, if_default);
 
     /* if we have a copy iface, parse that as well */
-    if (ConfGetChildValueWithDefault(if_root, if_default, "copy-iface", &out_iface) == 1) {
-        if (strlen(out_iface) > 0) {
-            if_root = ConfFindDeviceConfig(netmap_node, out_iface);
-            ParseNetmapSettings(&aconf->out, out_iface, if_root, if_default);
+    if (netmap_node != NULL) {
+        if (ConfGetChildValueWithDefault(if_root, if_default, "copy-iface", &out_iface) == 1) {
+            if (strlen(out_iface) > 0) {
+                if_root = ConfFindDeviceConfig(netmap_node, out_iface);
+                ParseNetmapSettings(&aconf->out, out_iface, if_root, if_default);
+            }
         }
     }