> > +      - items:
> > +          - const: renesas,r9a06g032-qspi
> 
> This should be enum, knowing how Renesas adds more devices.

In general, yes...

> 
> > +          - const: renesas,rzn1-qspi

... but this platform is old. We are at N2 meanwhile. Extremly likely
that no more N1 variants come out. And the other existing ones cannot
run Linux (no SDRAM interface). I think const is fine in this case.