staging: media: imx: add proper SPDX identifiers on files that did not have them.

There were a few files for the imx media drivers that did not have SPDX
identifiers on them, so fix that up.  At the same time, remove the "free
form" text that specified the license of the file, as that is impossible
for any tool to properly parse.

Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: linux-media@vger.kernel.org
Acked-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>