drm/i915: Remove spurious semicolons

Found by running the semicolon.cocci spatch:

  https://github.com/coccinelle/coccinellery/blob/master/semicolon/semicolon.cocci



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