fpga: versal-fpga: Remove empty functions

Since the core framework now wraps the functions, ensuring
drives only have to implement functions that do something,
drop the now no longer required callbacks for state and
write_complete.

Signed-off-by: Moritz Fischer <mdf@kernel.org>
Link: https://lore.kernel.org/r/20210726030806.714809-1-mdf@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>