Wrong ETA for max_seq_length != 512

[bartekkuncer]

Description

When you change max_seq_length value from 512 the ETA in eval_validation function does not end on 0.

Error Message

To Reproduce

Change max_seq_length to e.g. 128 and run e.g ~/gluon-nlp/scripts/question_answering/commands/run_squad2_uncased_bert_base.sh.