writerfilter: remove unused FBSE class in doctok

Change-Id: I46ad2bee7be304e84622af88bdd975963dcaf7e7
writerfilter: remove unused FOPTE class in doctok

Change-Id: I07cbdf3745ac8b2522397b8f013d9dcec8a894df
writerfilter: remove unused parts of the FSPA class in doctok

Change-Id: I44c4ee0ca9c9986b1479eb2a365d50319771b304