Simplify line expansion

GPU/Vulkan/DrawEngineVulkan.cpp

@@ -420,7 +420,6 @@ void DrawEngineVulkan::Flush() {
 				IndexBufferProvokingLastToFirst(prim, inds, vertexCount);
 			}
 		}
-		params.usesHalfZ = true;
 
 		// We need to update the viewport early because it's checked for flipping in SoftwareTransform.
 		// We don't have a "DrawStateEarly" in vulkan, so...