staging: comedi: ni_routes: Allow alternate board name for routes

staging: comedi: ni_routes: Allow alternate board name for routes

We do not have or provide routing information available for all
supported boards.  Some of the boards for which we do not currently
provide routing information actually have identical routes to a similar
board for which we do provide routing information.  To avoid having to
provide duplicate routing information, add an "alternate board name"
parameter (possibly `NULl`) to `ni_assign_device_routes()` and
`ni_find_device_routes()`.  If the routing information cannot be found
for the actual board name, try finding it using the alternate board
name.

Cc: Éric Piel <piel@delmic.com>
Cc: Spencer E. Olson <olsonse@umich.edu>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20200207151400.272678-3-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>