[PATCH] drbd: add missing kernel-doc for peer_device parameter

[Christoph Hellwig]

On Mon, Nov 17, 2025 at 10:55:56PM +0530, Sukrut Heroorkar wrote:
> W=1 build warns that peer_device is undocumented in the bitmap I/O
> handlers. This parameter was introduced in commit 8164dd6c8ae1
> ("drbd: Add peer device parameter to whole-bitmap I/O handlers"), but
> the kernel-doc was not updated.
> 
> Add the missing @peer_device entry.

Or just make it a non-kerneldoc comment as it doesn't document an
external API to start with.