media: ddbridge: constify stv0910_p and lnbh25_cfg

These structures are only copied into other structures, so
they can be const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>