libbt-vendor: rework structure of source code

Before complete implementation rework basic structure of code:
  - split actions to related functions
  - implement constants
  - remove useless log message
There aren't changes in logic.

Change-Id: I9cfa0782f78839f94085ab7d1b561925f34b5765
Signed-off-by: Andrii Beregovenko <a.beregovenko@ti.com>