fix loss normalization for ddp training

haoneng.lhn

2023-12-08 acb9a0fec8d8a4dabeedcbb8e08c26f66d7083f0

 egs/alimeeting/modular_sa_asr/README.md

@@ -99,5 +99,5 @@
|                |VBx DER(%)     | SOND DER(%)|cp-CER(%)  |
|:---------------|:------------:|:------------:|----------:|
|before finetune  |  16.87       |  1.51     |  10.18    |
|after finetune |     16.87    |   1.51   |          |
|after finetune |     16.87    |   1.51   |    **8.84**  |