drm/i915: Trivial grammar fix s/opt of/opt out of/ in comment

The word out was dropped from the sentence across the line break, put it
back.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20170816085210.4199-6-chris@chris-wilson.co.ukReviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -1346,7 +1346,7 @@ eb_relocate_entry(struct i915_execbuffer *eb,
 	 * patching using the GPU (though that should be serialised by the
 	 * timeline). To be completely sure, and since we are required to
 	 * do relocations we are already stalling, disable the user's opt
-	 * of our synchronisation.
+	 * out of our synchronisation.
 	 */
 	*vma->exec_flags &= ~EXEC_OBJECT_ASYNC;