Fix T52528: generated texture mismatch between Cycles and Eevee

Finally orco should be working 100% on Eevee now. Thanks for Sergey
Sharybin for reporting this.

source/blender/gpu/shaders/gpu_shader_material.glsl

@@ -3148,7 +3148,7 @@ void node_tex_coord(
         out vec3 generated, out vec3 normal, out vec3 uv, out vec3 object,
         out vec3 camera, out vec3 window, out vec3 reflection)
 {
-	generated = attr_orco * 0.5 + 0.5;
+	generated = attr_orco;
 	normal = normalize((obinvmat * (viewinvmat * vec4(N, 0.0))).xyz);
 	uv = attr_uv;
 	object = (obinvmat * (viewinvmat * vec4(I, 1.0))).xyz;