linux-wandboard

[media] siano: remove get_frontend stub

There's nothing at siano's get_frontend() callback. So,
remove it, as the core will handle it.

Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>