fix issue, when structure data type with array field is created

Traceback (most recent call last):
File "editors/DataTypeEditor.py", line 669, in ElementArrayTypeFunction
self.RefreshTypeInfos()
File "editors/DataTypeEditor.py", line 761, in RefreshTypeInfos
self.Controler.SetDataTypeInfos(self.TagName, infos)
File "PLCControler.py", line 2075, in SetDataTypeInfos
array.baseType.setcontent(PLCOpenParser.CreateElement(
AttributeError: 'lxml.etree._Element' object has no attribute 'setcontent'

                  <xsd:element name="Generic">
                    <xsd:complexType>
                      %(toolchain_makefile)s
                    </xsd:complexType>
                  </xsd:element>