ASoC: msm: Add support to change bit rate during VoIP call

Add support to change bit rate for AMR NB and AMR WB
vocoders while in VoIP call. This change is needed as part
of supporting VoWLAN feature.

Change-Id: Ic486dd7f48aca2c640b2364d00712741b50df4c8
Signed-off-by: Narsinga Rao Chella <nrchella@codeaurora.org>