[BUG] validate_yaml() isn't in sync with arguments check

[pierric]

Describe the bug
This check isn't in sync with the one in the arguments.py

To Reproduce

• in yaml config, pipeline_model_parallel_size = 2, and num_layers_per_virtual_pipeline_stage = 2
• pass --yaml-cfg

Expected behavior
The setting pipeline_model_parallel_size = 2 should be accepted.

Proposed fix
sync up the check in the two places.

[junjzhang]

if you use yaml_cfg, args will only be parsed with yaml.

[pierric]

I know. but I mean --pipeline-model-parallel-size=2 --num-layers-per-virtual-pipeline-stage=2 is accepted, while on the other hand being rejected as in a yaml and with a --yaml-cfg. It's inconsistent.