serial: sh-sci: Fix up default regtype probing.

Presently the default regtype probing inadvertently bails out due to an
inverted error check. This fixes it up, and gets platforms without
explicit regtype specifications working again.
Reported-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

drivers/tty/serial/sh-sci.c

@@ -1889,7 +1889,7 @@ static int __devinit sci_init_single(struct platform_device *dev,
 
 	if (p->regtype == SCIx_PROBE_REGTYPE) {
 		ret = sci_probe_regmap(p);
-		if (unlikely(!ret))
+		if (unlikely(ret != 0))
 			return ret;
 	}