core: Fix FindBugs filter for XmlNode.innerText

Commit d377d275416edbbd3f4b1d57047ee04840412bba renamed
XmlNode's InnerText field to innerText, but neglected to update the
FindBugs filter referring to it.

This patch corrects that mistake.

Change-Id: Ibf2e1958319b62ac4fa02c3131614c26233a4ef0
Signed-off-by: Allon Mureinik <amureini@redhat.com>