media: dvb-frontends/cxd2099: add SPDX license identifier

As both the MODULE_LICENSE and the boilerplates are now in sync and clear
that the driver is licensed under the terms of the GPLv2-only, add a
matching SPDX license identifier tag.

Cc: Ralph Metzler <[e-mail]>
Cc: Manfred Voelkel <[e-mail]>
Signed-off-by: Daniel Scheller <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb-frontends/cxd2099.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * cxd2099.c: Driver for the Sony CXD2099AR Common Interface Controller
  *

drivers/media/dvb-frontends/cxd2099.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * cxd2099.h: Driver for the Sony CXD2099AR Common Interface Controller
  *