Static layout PNOR support in openpower-pnor-code-mgmt

[Lei YU]

> >> Is this a new format? Why? Where is it documented?
> >>
> >
> > Looking on gerrit this just appears to be the PNOR and a MANIFEST file in
> > a tarball. Considering it's just a call to 'tar', having it be generated
> > by something called 'generate-squashfs' is confusing. I guess this is
> > because generate-squashfs creates the MANIFEST file?
>
> Yeah, that sounds odd. The current format is just the pnor file.

Yeah, it is a bit odd, I just want to re-use the code in 'generate-squashfs'
to generate a tar that contains MANIFEST and the pnor.
Possibly it could be renamed to `generate-tar`or similar.
Be noted that this file is used to generate Witherspoon's PNOR tarball in
op-build. So renaming it should cause op-build to pick the new name.