Fix error range for cvc-elt.3.2.1

[fbricon]

given this schema foo.xsd

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:element
            name="root"
            nillable="true">
        <xsd:complexType>
            <xsd:sequence>
                <xsd:element
                        name="e1"
                        type="xsd:string"/>
            </xsd:sequence>
        </xsd:complexType>
    </xsd:element>
</xsd:schema>

This invalid xml has a wrong diagnostic range:

<root
        xsi:noNamespaceSchemaLocation="foo.xsd"
        xsi:nil="true"
        xmlns=""
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <e1>xxx</e1>
</root>