msm: vidc: add support for bitrate_type control

When setting layer wise bitrates, firmware accumulates all bitrates
and re-distributes them to each layer. This change ensures firmware
honors layer wise/cumulative bitrate settings.

Change-Id: Iefe6f1b89eb45c6f585a5d19e5204eccb0fdb63f
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>