kmssink: need check scaleable when start
Submitted by Haihua Hu
I create a new thread for this issue. Please refer to this link for detail info:https://bugzilla.gnome.org/show_bug.cgi?id=784599
There is a bug when driver not support scale. when video size is same as display resolution, show frame will not do retry because the setplane will never fail. But the scale result is not correct. We can do this check by set a fake plane.
This bug will impact the videooverlay interface, because the implementation is based on driver scaleable capability.