Minor wording changes and use qemu max option

Improve the wording in the comments.
Use -cpu max instead of -cpu any because "max" is the documented alias
of "any".
Add NFS related messages to be ignored by dejagnu.
These are all changes from the refactored oban-scripts.
For more information, see
https://jira.arm.com/browse/GNUTOOLS-15450

Change-Id: I8da4806a370663b3f2b5e0eefebced84afa4f9a9