drm/i915: Don't use a define when it's clearer to just put the value

Instead of going through hoops, just put the driver author directly as
DRM_AUTHOR() argument. This will also make it consistent when we add
Intel to the list.

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>