Revert "msm: vidc: Ignore bus votes with no load"

Go back to voting for the minimum vector for each bus as ignoring bus
votes had adverse side effects with concurrent sessions.

This reverts commit d2c1afd8.

Change-Id: Iacf3a738e90359edc6fd3c425ba068e9cf808657
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>