[BugFix] Update parallel.py (#1905)

Author: ZHUI

paddlenlp/ops/distributed/parallel.py

@@ -230,7 +230,7 @@ def forward(self, x):
         if self.gather_out is False:
             return output_parallel
 
-        return paddle.distributed.collective._concat(
+        return paddle.distributed.collective._c_concat(
             output_parallel, group=group)