coda: fix encoder rate control parameter masks

This patch fixes the ENC_SEQ_RC_PARA initial delay and bitrate masks.
These bit fields are 15 bit wide, not 7 bit.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
coda: bitrate can only be set in kbps steps

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>