Enabling passthorugh mode is causing multiple issue:
For nal aligned multiresoluton streams, passthrough mode
make h264parse unable to advertise the new resoultions.
Also causing issues while parsing MVC streams which have two
separate layers (base-view and non-base-view).

This fix is only a temporary workaround.

For MVC, proper fixes needed in many places:
(handle prefix nal unit, handle non-base-view slice nal extension,
fix the picture_start detection for multi-layer-mvc streams etc)

https://bugzilla.gnome.org/show_bug.cgi?id=758656