Revert "i965/miptree: Set logical_depth0 == 6 for cube maps"

This reverts commit 48e9ecc47f078cba3f56694e4583003681717410.

The commit regressed several piglit tests on SNB/ILK hardware.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97567
1 file changed