EEVEE-Next: Fix shader compilation error.

Due to a copy-paste error there was an out of bound read. Some drivers
didn't complain about it, others did. This patch fixes the compilation
error by accessing the array within bounds.

source/blender/draw/intern/shaders/common_intersect_lib.glsl

@@ -353,8 +353,7 @@ bool intersect(IsectFrustum i_frustum, Box box)
 bool intersect(IsectFrustum i_frustum, Sphere sphere)
 {
   bool intersects = true;
-
-  for (int p = 0; p < 8; ++p) {
+  for (int p = 0; p < 6; ++p) {
     float dist_to_plane = dot(i_frustum.planes[p], vec4(sphere.center, 1.0));
     if (dist_to_plane < -sphere.radius) {
       intersects = false;