V4L/DVB (9015): S2API: cx24116 register description fixes.

From the author:
Here is a simple patch detailing some reverse engineered
register detail lost in my latest merge. The comments
in the code refer to this register but it is never
defined. This corrects this.

Signed-off-by: Steven Toth <stoth@linuxtv.org>
Signed-off-by: Darron Broad <darron@kewl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>