[media] remove radio-maestro

Remove broken radio-maestro driver as the radio functionality is now
integrated in the es1968 driver.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Acked-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>