Fix #35473: Using Redo panel in View3D after Grease Pencil action moves GP layer to that area

Remove REGISTER flag from GP draw operator, so redo wouldn't screw up regions.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57074 954f8c5b-7b00-dc11-b283-0030488c597c