[PATCH] nvme: add nvme_is_disc_subsys() helper

[Christoph Hellwig]

On Wed, Oct 28, 2026 at 09:04:03PM +0530, Martin George wrote:
> No bigger plans - it's just a small cleanup. Mainly two things:
> 
> - Consistency with the target, which already has something similar
> - It folds the open-coded discovery subtype checks into one self-
> documenting helper for current & future use.
> 
> So a minor net improvement rather than a prerequisite for anything.

Not sure a helper is more self-documenting than a field check.

I don't really care strongly, but this feels a bit like churn without
a real purpose to me.