radv: fix a sync issue on GFX9+ by clearing the upload BO fence
If the same cmdbuf is submitted more than once, they were waiting on the same fence value. Fix this by clearing the value when beginning a new command buffer. This might fix spurious GPU hangs, especially on GFX9. Closes: mesa/mesa#5401 Cc: 21.3 mesa-stable Signed-off-by:Samuel Pitoiset <samuel.pitoiset@gmail.com> Reviewed-by:
Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> Part-of: <mesa/mesa!13777> (cherry picked from commit e94a899c)