V4L/DVB (6834): cx88-video: Enable selection of the WM8775 for cx88 cards

The auto selection of pertinent helper chips (VIDEO_HELPER_CHIPS_AUTO)
should select the wm8775 driver, which is used by at least one
Conexant 2388x based card (Hauppauge HVR-1300), if VIDEO_CX88 is
selected.

Signed-off-by: Frej Drejhammar <frej.drejhammar@gmail.com>
Signed-off-by: Ricardo Cerqueira <v4l@cerqueira.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>