vfio/mdev: Fix spelling mistake "interal" -> "internal"

There is a spelling mistake in a comment, fix it.
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20210326083528.1329-3-thunder.leizhen@huawei.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/mdev/mdev_private.h

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Mediated device interal definitions
+ * Mediated device internal definitions
  *
  * Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
  *     Author: Neo Jia <cjia@nvidia.com>