[media] tda8261: don't use set_state/get_state callbacks

Those callbacks are meant to be used only on some very specific
cases. There's absolutely no need to do that at tda8261, as
the only parameter that it allows to be set/get is the frequency.

So, use the standard get_params() and get_frequency() kABI
ops.

There's no need to touch at any bridge driver, as all interactions
are done via the macros at tda8261_cfg.h.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>