radeonsi: only do VGT_FLUSH for fast launch if previous draw was normal launch

Fixes: 3da91b3327f - radeonsi/ngg: add VGT_FLUSH when enabling fast launch

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7542>
(cherry picked from commit 8d2876a34314e7378eff67a5f320eba56683dba3)
3 files changed