[PATCH] nvme-auth: use IS_REACHABLE for nvme_auth_extract_key() declaration

[Keith Busch]

On Mon, Nov 03, 2025 at 12:46:21PM +0100, Christoph Hellwig wrote:
> So with Keith' latest fixes the auth code should always be built
> in if either the host or target code is built in.  Did this not
> work, or is this for an older branch?

It should be fine if either or both are built in. The problem is if both
are modules. For that config, this should have used:

#ifdef CONFIG_NVME_AUTH_STATE

Or IS_REACHABLE also works.