V4L/DVB (7086): driver: tcm825x - fix logical typo error

This patch does fix potential NULL pointer dereference
due to logical typo error.

The issue is pointed out by
Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>


Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
CC: Sakari Ailus <sakari.ailus@nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>