staging: comedi: ni_stc.h: remove unused GPCT register bit defines

The bit defines in this header for the GPCT registers are not used. The ones
in ni_tio_internal.h are used instead. Remove them from this header.

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