powerpc/vio: use strcpy in modalias_show

Commit e82b89a6 used strcat instead of
strcpy which can result in an overflow of newlines on the buffer.

Signed-off-by: Prarit Bhargava
Cc: benh@kernel.crashing.org
Cc: ben@decadent.org.uk
Cc: stable@vger.kernel.org
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/vio.c

@@ -1531,12 +1531,12 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
 
 	dn = dev->of_node;
 	if (!dn) {
-		strcat(buf, "\n");
+		strcpy(buf, "\n");
 		return strlen(buf);
 	}
 	cp = of_get_property(dn, "compatible", NULL);
 	if (!cp) {
-		strcat(buf, "\n");
+		strcpy(buf, "\n");
 		return strlen(buf);
 	}