mesa: vdpau fixes assert in debug mode
When compiled in debug mode assert comes up. st_get_texture_sampler_view_from_stobj: Assertion `stObj->level override || last level(stObj) == view->u.tex.last level' failed.
_mesa_test_texobj_completeness sets max_level to -1 because t->NumLevels - 1, and immutable texture and NumLevels = 0.
Should fix https://bugs.freedesktop.org/show_bug.cgi?id=107666