msm: vidc: Use min_dpb from resource tracker in smooth streaming mode

Get min_dpb from resource tracker always if smooth streaming
mode is enabled to handle number of output buffers properly.

Change-Id: Ic46f76061f3895fda44e1d8e94198f898e5edf9b
Signed-off-by: Deepak Verma <dverma@codeaurora.org>