[PATCH v4] linux-gen: ml: a few small fixes and cleanups

[JereLeppanen]

v2:

• Rebase.
• Check for null pointers in linux-gen: ml: slightly simplify clean up in error cases in odp_ml_run()
• Add commit linux-gen: ml: clean up error handling in verify_tensor()

[JereLeppanen]

v3:

• Update copyright in first commit.
• Add review tags.