v3dv: fix scissor outside viewport

In this scenario we can end up generating a clip window where
the max coordinates are smaller than the min coordinates and the simulator
asserts.

Fixes:
dEQP-VK.draw.scissor.dynamic_scissor_outside_viewport
dEQP-VK.draw.scissor.static_scissor_outside_viewport

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>
1 file changed