[media] coda: add h.264 min/max qp controls

If the bitrate control is set, the encoder works in CBR mode, dynamically
changing the quantization parameters to achieve a constant bitrate.
With the min/max QP controls the quantization parameters can be limited
to a given range.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>