intel: Remove the texture_tiling driconf option.

intel: Remove the texture_tiling driconf option.

This option can force textures to be untiled.  However, on Gen6+, depth
buffers must be Y-tiled.  MSAA buffers also must be Y-tiled.  So setting
this option on even a trivial application like glxgears causes assertion
failures in a debug build, and likely GPU hangs in a release build.

It's just giving users a license to shoot themselves in the foot.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>