msm: vidc: Add support for layer bitrate

Enables layer and cumulative bitrate based on client's input.
Layer bitrate ratio provided by client is checked for correctness
and converted into layer bitrate.
Fix hierp by adding layer count check.

Change-Id: I2e878004a0f518258f89cc5b34823106f2f727f1
Signed-off-by: Amit Shekhar <ashekhar@codeaurora.org>