media: remove dead TI wl128x FM radio driver

Commit 78fe6636 ("misc: ti-st: st_kim: remove the driver") deletes the
ti-st driver and its corresponding config option TI_ST.

With that deletion, the Texas Instruments WL128x FM Radio driver is now
dead as well. Delete this obsolete driver.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>