msm: vidc: fix setting of client buffer count

The client requested buffer count was not honoured
in specific case - when requested buffer count
was less than actual buffer count, but greater than
min buffer count. It would be set to the min buffer
count, which would fail playback.

Change-Id: I10859fd2cb309b8f2b4fb106f9a78f4dc46d45ed
Signed-off-by: Arun Menon <avmenon@codeaurora.org>