COMP: Additional const-correctness fix for new DataNode method

The previous pull request had not been rebased against master for a
while so it was missing a fix for a new DataNode method that has the
same const-correctness problem on the renderer parameter.

Signed-off-by: Taylor Braun-Jones <taylor.braun-jones@ge.com>
Merge branch 'bug-16028-DataNode-const-correct-params'

* bug-16028-DataNode-const-correct-params:
  COMP: Additional const-correctness fix for new DataNode method