mm-video: vidc: Fix testapp to display decoded frames

After the vsync changes to overlay, any module that
uses overlay should enable vsync control before
setting the overlay. Changes are made to enable
or disable vsync control and also added pan display
ioctl after overlay play

CRs-fixed: 410162
Change-Id: Idc5ae4d05726cb9029b219d794e6cbaa8b2a2f71
1 file changed