msm: vidc: consider max of dpb-opb resolutions to pick proper ab value

In case of down scalar enabled, opb resolution is considered to
pick bus vector. update bus voting date width and height with
max of dpb-opb resolutions to vote appropriate bus vector.

Change-Id: I10ed10a86c45c7ba3dfe96e44f7a44e6d2a7a79d
Signed-off-by: Srinu Gorle <sgorle@codeaurora.org>