staging: comedi: remove 'settling_time_0' from subdevice

The `settling_time_0` member of `struct comedi_subdevice` can be set by
a low-level comedi driver and will be copied to user-space as part of
the information provided by the `COMEDI_SUBDINFO` ioctl.  No comedi
driver has ever set it; it's just been left at its initial value of 0.
Remove it to save a bit of space, and behave as though it is 0.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/comedi_fops.c

@@ -826,8 +826,6 @@ static int do_subdinfo_ioctl(struct comedi_device *dev,
 			us->insn_bits_support = COMEDI_SUPPORTED;
 		else
 			us->insn_bits_support = COMEDI_UNSUPPORTED;
-
-		us->settling_time_0 = s->settling_time_0;
 	}
 
 	ret = copy_to_user(arg, tmp, dev->n_subdevices * sizeof(*tmp));

drivers/staging/comedi/comedidev.h

@@ -57,8 +57,6 @@ struct comedi_subdevice {
 	unsigned int maxdata;	/* if maxdata==0, use list */
 	const unsigned int *maxdata_list;	/* list is channel specific */
 
-	unsigned int settling_time_0;
-
 	const struct comedi_lrange *range_table;
 	const struct comedi_lrange *const *range_table_list;