NotImplementedError: Model's DEFAULT_TRAIN_BSIZE is not implemented. (#2563)

Summary:
Some tests fail in train mode. I found missing fields in specific models and added DEFAULT_TRAIN_BSIZE with the same value as eval batch size.

Pull Request resolved: #2563

Reviewed By: adamomainz

Differential Revision: D69786156

Pulled By: xuzhao9

fbshipit-source-id: aedf72d758d31e59f3c9b611d1ae0a46fee7c7f4

Author: ostrowskimarcin

torchbenchmark/models/cm3leon_generate/__init__.py

@@ -7,6 +7,7 @@
 
 class Model(BenchmarkModel):
     task = NLP.LANGUAGE_MODELING
+    DEFAULT_TRAIN_BSIZE = 1
     DEFAULT_EVAL_BSIZE = 1
 
     def __init__(self, test, device, batch_size=None, extra_args=[]):