staging: comedi: cb_pcidda: fix error test in cb_pcidda_attach_pci()

As pointed out by Fengguang Wu, the error test after finding the
boardinfo should be testing for (!thisboard).

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/cb_pcidda.c

@@ -657,7 +657,7 @@ static int cb_pcidda_attach_pci(struct comedi_device *dev,
 	int ret;
 
 	thisboard = cb_pcidda_find_boardinfo(dev, pcidev);
-	if (!pcidev)
+	if (!thisboard)
 		return -ENODEV;
 	dev->board_ptr = thisboard;
 	dev->board_name = thisboard->name;