[media] radio-sf16fmr2: Remove redundant dev_set_drvdata

Driver core sets driver data to NULL upon failure or remove.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>