staging: comedi: ni_mio_common: implement global pfi, rtsi routing

Implement device-global config interface for ni_mio devices.  In
particular, this patch implements:
INSN_DEVICE_CONFIG_TEST_ROUTE,
INSN_DEVICE_CONFIG_CONNECT_ROUTE,
INSN_DEVICE_CONFIG_DISCONNECT_ROUTE,
INSN_DEVICE_CONFIG_GET_ROUTES
for the ni mio devices.  This means that the new abstracted signal/terminal
names can be used to define signal routing with regards to the PFI
terminals and RTSI trigger bus lines.

This also adds ability to identify PFI and RTSI channels on the PFI and
RTSI subdevices using the new device-global names.  This does not change
the values that are set for channel output selections using the subdevice
interfaces--these still require direct register values.

Annotates and updates tables of register values to reflect this new
implementation status.

Signed-off-by: Spencer E. Olson <olsonse@umich.edu>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>