staging: comedi: gsc_hpdi: remove multiple board type support

The code for determining which board type matches the PCI device ID is
over-the-top since only a single board type is supported.  Also, the
method it uses match the PCI device ID to a board type is a little
antiquated.  Most comedi drivers for PCI devices use `driver_data` from
the probed PCI device as an index into an array of supported board
types, but "gsc_hpdi" uses a `for` loop to find an element of
`hpdi_boards[]` that matches the PCI device.  The only thing in
`hpdi_boards[]` not used for finding a matching PCI device is the `name`
member of `struct hpdi_board` which points to a string literal and ends
up getting assigned to `dev->board_name`.

Get rid of the multiple board type support, and set `dev->board_name` to
point to the original string literal pointed to by
`hpdi_boards[0].name`.  This string is visible to userspace.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>