drm/i915: unbreak i915_gem_object_ggtt_unbind()

There is an extra semi-colon here so we just leak and never unbind
anything.

This regression has been introduced in

commit 07fe0b12
Author: Ben Widawsky <ben@bwidawsk.net>
Date:   Wed Jul 31 17:00:10 2013 -0700

    drm/i915: plumb VM into bind/unbind code

Cc: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -2664,7 +2664,7 @@ i915_gem_object_ggtt_unbind(struct drm_i915_gem_object *obj)
 	struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
 	struct i915_address_space *ggtt = &dev_priv->gtt.base;
 
-	if (!i915_gem_obj_ggtt_bound(obj));
+	if (!i915_gem_obj_ggtt_bound(obj))
 		return 0;
 
 	if (obj->pin_count)