staging: comedi: coding style fixes found by checkpatch.pl

The patch removes "WARNING: Prefer using '"%s...", __func__'
to using 'xxxxxxxx', this function's name, in a string" warnings
reported by checkpatch.pl script.
Signed-off-by: Simo Koskinen <koskisoft@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers.c

@@ -995,12 +995,12 @@ int comedi_auto_config(struct device *hardware_device,
 	int ret;
 
 	if (!hardware_device) {
-		pr_warn("BUG! comedi_auto_config called with NULL hardware_device\n");
+		pr_warn("BUG! %s called with NULL hardware_device\n", __func__);
 		return -EINVAL;
 	}
 	if (!driver) {
 		dev_warn(hardware_device,
-			 "BUG! comedi_auto_config called with NULL comedi driver\n");
+			 "BUG! %s called with NULL comedi driver\n", __func__);
 		return -EINVAL;
 	}