staging: comedi: comedi_bond: use correct minor device numbers in name

The board name for "comedi_bond" is constructed from a space-separated
list of items of the form "minor:subdevice" where "minor" is a minor
device number and "subdevice" is a subdevice number.  Currently, all the
"minor" device numbers are for the "comedi_bond" device itself and the
"subdevice" numbers are for the bonded devices.  It makes makes more
sense for the "minor" device numbers to come from the bonded devices as
well so that the string is a list of bonded "minor:subdevice" pairs.
Fix it.

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