LU-11085 nodemap: switch interval tree to in-kernel impl.

LU-11085 nodemap: switch interval tree to in-kernel impl.

Switch nodemap_range to use the in-kernel interval tree.
This has the same functionality, though often in a different form.

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I7bf119bf8cd8f14dc66deb2736c2c97562bb0743
Reviewed-on: https://review.whamcloud.com/39724
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>