staging: comedi: jr3_pci: Reset all DSPs

The various JR3 PCI models have from 1 to 4 DSPs, one per subdevice.
Prior to loading the firmware to all the DSPs, the initialization code
in `jr3_pci_auto_attach()` resets the first DSP.  As far as I can tell,
it should reset all of them.  Change it to do so.

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