ds1338: Add missing break statement

Without the break statement, case 5 sets month and year from the same
data. This does not look correct.

The missing break was reported by splint.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/hw/ds1338.c b/hw/ds1338.c
index 6397f0a..d590d9c 100644
--- a/hw/ds1338.c
+++ b/hw/ds1338.c
@@ -100,6 +100,7 @@
             break;
         case 5:
             s->now.tm_mon = from_bcd(data & 0x1f) - 1;
+            break;
         case 6:
             s->now.tm_year = from_bcd(data) + 100;
             break;