Add generic utility to track range conflicts signaled by a dma-fence.
Tracking implemented via an interval tree. An example use case being
tracking conflicts for pending (un)binds from multiple bind engines. By
being generic ths idea would this could moved to the DRM level and used
in multiple drivers for similar problems.

v2: Make interval tree functions static (CI)
v3: Remove non-static cleanup function (CI)
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>