media: dib7000p: make static read-only arrays notch and sine const

The static arrays notch and sine are read-only so it make sense
to make them const.

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