msm: vidc: add driver support for multiple bframe encoding

Video hardware supports setting upto three consecutive bframes.
Current driver setting allowed only one bframe in output. This
change configures firmware to have upto three b frames in output.

Change-Id: I4cc02776df3587d11cca5477c7d657aea84f34ba
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>