[media] redrat3: fix transmit return value and overrun

If more than 127 different lengths are transmitted then the driver causes
an overrun on sample_lens. Try to send as much as possible and return the
amount sent.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>