Adopt the SPDX license identifier headers to ease license compliance
management. All files in the driver are licensed under the GPLv2+ except
for the vsp1_regs.h file which is licensed under the GPLv2. This is
likely an oversight, but fixing this requires contacting the copyright
owners and is out of scope for this patch.

While at it fix the file descriptions to match file names where copy and
paste error occurred.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>