radio-tea5761: Update driver

radio-tea5761: Update driver

This patch updates this driver by changing the way it accesses
the device. There is the tuner API which already has an implementation
for tea5761.

This patch changes the driver to use tuner API.

It also changes the way ioctls are handled. This way
it is more easy to deal with v4l2 and v4l calls.

Some cleans are also done.

Signed-off-by: Eduardo Valentin <eduardo.valentin@indt.org.br>
Signed-off-by: Tony Lindgren <tony@atomide.com>