v3dv: fix viewport Z

Vulkan has Z NDC range in [0, 1], we where using OpenGL's [-1, 1].

Fixes:
dEQP-VK.draw.inverted_depth_ranges.nodepthclamp_deltasmall
dEQP-VK.draw.inverted_depth_ranges.nodepthclamp_deltaone

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