drm/i915: Removed IVB forced enable of sprite dest key.

The destination color key is always enabled for IVB.  Removed
the line that does this.

Signed-off-by: Armin Reese <armin.c.reese@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: stable@kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sprite.c

@@ -95,7 +95,6 @@ ivb_update_plane(struct drm_plane *plane, struct drm_framebuffer *fb,
 	/* must disable */
 	sprctl |= SPRITE_TRICKLE_FEED_DISABLE;
 	sprctl |= SPRITE_ENABLE;
-	sprctl |= SPRITE_DEST_KEY;
 
 	/* Sizes are 0 based */
 	src_w--;