Be nice. There are evidentally a number of different cards that

identify themselves as serial cards that it would be desirable to
attach a different driver than sio to.  Since we are claiming all
serial cards, this is not possible.  Instead, return -100 to indicate
that we're willing to take the card, but still allow other drivers to
attach.

Pointed out by: Maksim Yevmenkin

sys/dev/sio/sio_pccard.c

@@ -80,10 +80,12 @@ sio_pccard_match(device_t dev)
 	if (error != 0)
 		return (error);
 	/*
-	 * If a serial card, we are likely the right driver.
+	 * If a serial card, we are likely the right driver.  However,
+	 * some serial cards are better servered by other drivers, so
+	 * allow other drivers to claim it, if they want.
 	 */
 	if (fcn == PCCARD_FUNCTION_SERIAL)
-		return (0);
+		return (-100);
 
 	return(ENXIO);
 }