[PATCH] drm/prime: Remove duplicate forward declaration

[Chris Wilson]

Quoting Thierry Reding (2018-01-11 20:17:30)
> From: Thierry Reding <treding at nvidia.com>
> 
> struct device is forward-declared twice. Remove the second instance.

So good they declared it twice. Also the first one first in with the
alphabetical ordering.
 
> Signed-off-by: Thierry Reding <treding at nvidia.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris