network: Don't unlock non-locked network driver

In dd7bfb2cdc I've removed locking of the network driver upon
it's allocation. However, I forgot to remove one location of the
driver unlock.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

src/network/bridge_driver.c

@@ -718,8 +718,6 @@ networkStateInitialize(bool privileged,
     return ret;
 
  error:
-    if (network_driver)
-        networkDriverUnlock(network_driver);
     networkStateCleanup();
     goto cleanup;
 }