The base hmm MMU code doesn't support contiguous allocations (they BUG), so
remove support from them from the higher levels of the heirarchy.

We still need to unwind all these layers but it turns out that some of the init
order stuff is rather sensitive and the simple cleanup breaks everything
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>