Make default SBC bitrate configurable by device.

Configurable default SBC bitrate so that audio quality can be maintained
for sampling rates other than 44.1kHz

Change-Id: Ia4197c0a500088cfa48a8ba821e9738a16c3fc6e
Signed-off-by: Sridhar Vashist <svashist@motorola.com>
(cherry picked from commit d4e7035d)