fix clip conf

Author: zh794390558

examples/aishell/s1/conf/chunk_conformer.yaml

@@ -79,7 +79,7 @@ model:
 
 training:
   n_epoch: 180
-  accum_grad: 1
+  accum_grad: 4
   global_grad_clip: 5.0
   optim: adam
   optim_conf:

examples/aishell/s1/conf/conformer.yaml

@@ -76,7 +76,7 @@ model:
 training:
   n_epoch: 240 
   accum_grad: 2
-  global_grad_clip: 3.0
+  global_grad_clip: 5.0
   optim: adam
   optim_conf:
     lr: 0.002