media: dvb-usb: m920x: make read-only arrays static const

Don't populate the arrays on the stack, instead make them static
const. Also makes the object code smaller.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>