[media] stih-cec/vivid/pulse8/rainshadow: use cec_transmit_attempt_done

Use the helper function cec_transmit_attempt_done instead of
cec_transmit_done to simplify the code.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>