staging: comedi: remove comedi_fc module

All the exported functions in the "comedi_fc" module have been migrated
to the core "comedi" module and renamed, so it is now just a dummy
module.  Remove it.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>