msm: vidc: Fix buffer count related issues

This change fixes various buffer counts in driver by
properly updating them based on state.

CRs-Fixed: 2066658
Change-Id: Iec37d67b88f8a6d06776a8cfba7d9812662d5325
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>