drbd: Remove superfluous newline from "resync_extents" debugfs entry.

See "drbd/resources/*/volumes/*/resync_extents".

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>