radv: Fix condition for skipping the continue CS.

We need the continue CS for referencing the tess/GDS/sample position BOs.

Fixes: 46e52df3 "radv: add tessellation ring allocation support. (v2)"
Fixes: e1dc3ab7 "radv/gfx10: allocate GDS/OA buffer objects for NGG streamout"
Fixes: 1171b304 "radv: overhaul fragment shader sample positions."
Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
(cherry picked from commit 8ad3d8b1)