[CORE] Bugfix: LogErr format in DAGScheduler.scala

Author: Zhang, Liye <liye.zhang@intel.com>

Closes #2572 from liyezhang556520/DAGLogErr and squashes the following commits:

5be2491 [Zhang, Liye] Bugfix: LogErr format in DAGScheduler.scala

(cherry picked from commit 657bdff41a27568a981b3e342ad380fe92aa08a0)
Signed-off-by: Reynold Xin <rxin@apache.org>