Fix return value in lock manager hotplug methods

Refactoring of the lock manager hotplug methods lost the
ret = 0 assignment for successful return path

* src/locking/domain_lock.c: Add missing ret = 0 assignments

src/locking/domain_lock.c

@@ -221,6 +221,8 @@ int virDomainLockDiskAttach(virLockManagerPluginPtr plugin,
     if (virLockManagerAcquire(lock, NULL, 0) < 0)
         goto cleanup;
 
+    ret = 0;
+
 cleanup:
     virLockManagerFree(lock);
 
@@ -240,6 +242,8 @@ int virDomainLockDiskDetach(virLockManagerPluginPtr plugin,
     if (virLockManagerRelease(lock, NULL, 0) < 0)
         goto cleanup;
 
+    ret = 0;
+
 cleanup:
     virLockManagerFree(lock);
 
@@ -260,6 +264,8 @@ int virDomainLockLeaseAttach(virLockManagerPluginPtr plugin,
     if (virLockManagerAcquire(lock, NULL, 0) < 0)
         goto cleanup;
 
+    ret = 0;
+
 cleanup:
     virLockManagerFree(lock);
 
@@ -279,6 +285,8 @@ int virDomainLockLeaseDetach(virLockManagerPluginPtr plugin,
     if (virLockManagerRelease(lock, NULL, 0) < 0)
         goto cleanup;
 
+    ret = 0;
+
 cleanup:
     virLockManagerFree(lock);