[media] cx231xx: fix GPIOs for Pixelview SBTVD hybrid

This device uses GPIOs: 28 to switch between analog and
digital modes: on digital mode, it should be set to 1.

The code that sets it on analog mode is OK, but it misses
the logic that sets it on digital mode.

Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>