V4L/DVB (7672): dib7000p: Add output mode param to the attach struct

This allows future drivers to select the most appropriate output mode.

Signed-off-by: Steven Toth <stoth@hauppauge.com>
Reviewed-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>