ilo: convert GPE state functions to use ilo_builder

Make these changes

  ilo_cp_steal_ptr() and memcpy() -> ilo_builder_state_write()
  ilo_cp_steal_ptr()              -> ilo_builder_state_pointer()

and use this chance to drop the "_emit_" infix.
ilo: convert GPE GEN7 command functions to use ilo_builder

Make these changes

  ilo_cp_begin()    -> ilo_builder_batch_pointer()
  ilo_cp_write()    -> direct memory set
  ilo_cp_write_bo() -> ilo_builder_batch_reloc()

and use this chance to drop the "_emit_" infix.
ilo: convert GPE GEN6 command functions to use ilo_builder

Similar to the changes to GEN7 command functions, but to GEN6 this time.
ilo: remove unused ilo_cp functions

Remove

  ilo_cp_begin()
  ilo_cp_steal()
  ilo_cp_write()
  ilo_cp_write_multi()
  ilo_cp_write_bo()
  ilo_cp_end()
  ilo_cp_steal_ptr()