USB: chipidea: ci_hdrc_tegra.c: add SPDX line

The license text was removed from this file, yet they somehow missed
the big "add SPDX tags to all files" sweep due to them being new.  So
add the proper SPDX license tag to them, based on the original license
text in the file.

Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Acked-by: NPeter Chen <peter.chen@nxp.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/chipidea/ci_hdrc_tegra.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2016, NVIDIA Corporation
  */