drm/i915: Make some string arrays const

Most of our char* arrays are markes as const already, but a few slipped
through the cracks. Fix it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
1 file changed