msm: vidc: Update the minimum supported bit rate for encoder

Venus FW supports minimum bit rate of 32kbps. This change updates
the kernel driver to allow the clients to configure bit rate from
32kbps to 160mbps.

Change-Id: I1663275a5f8affcdad545d1e7e73ab7c5d229ebe
CRs-Fixed: 494836
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>