storage: No need to check ret after VIR_APPEND_ELEMENT

Generates a false positive for Coverity, but it turns out there's no need
to check ret == -1 since if VIR_APPEND_ELEMENT is successful, the local
vol pointer is cleared anyway.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/storage/storage_backend_logical.c

@@ -307,7 +307,7 @@ virStorageBackendLogicalMakeVol(char **const groups,
     ret = 0;
 
  cleanup:
-    if (is_new_vol && (ret == -1))
+    if (is_new_vol)
         virStorageVolDefFree(vol);
     return ret;
 }

src/storage/storage_backend_zfs.c

@@ -161,7 +161,7 @@ virStorageBackendZFSParseVol(virStoragePoolObjPtr pool,
  cleanup:
     virStringFreeList(tokens);
     virStringFreeList(name_tokens);
-    if (is_new_vol && (ret == -1))
+    if (is_new_vol)
         virStorageVolDefFree(volume);
     return ret;
 }