icmpv6: Fix Coverity warnings on ND_* types

This patch fixes:
** CID 1187544:  Missing break in switch  (MISSING_BREAK)
/src/decode-icmpv6.c: 268 in DecodeICMPV6()

** CID 1187545:  Missing break in switch  (MISSING_BREAK)
/src/decode-icmpv6.c: 270 in DecodeICMPV6()

** CID 1187546:  Missing break in switch  (MISSING_BREAK)
/src/decode-icmpv6.c: 272 in DecodeICMPV6()

** CID 1187547:  Missing break in switch  (MISSING_BREAK)
/src/decode-icmpv6.c: 274 in DecodeICMPV6()

It duplicates the logic instead of adding 'fall through' statements
as the debug statements were wrong and confusing. For ND_REDIRECT
all 5 ND_* types would have been printed.

src/decode-icmpv6.c

@@ -265,19 +265,33 @@ int DecodeICMPV6(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p,
             break;
         case ND_ROUTER_SOLICIT:
             SCLogDebug("ND_ROUTER_SOLICIT");
+            if (p->icmpv6h->code != 0) {
+                ENGINE_SET_EVENT(p, ICMPV6_UNKNOWN_CODE);
+            }
+            break;
         case ND_ROUTER_ADVERT:
             SCLogDebug("ND_ROUTER_ADVERT");
+            if (p->icmpv6h->code != 0) {
+                ENGINE_SET_EVENT(p, ICMPV6_UNKNOWN_CODE);
+            }
+            break;
         case ND_NEIGHBOR_SOLICIT:
             SCLogDebug("ND_NEIGHBOR_SOLICIT");
+            if (p->icmpv6h->code != 0) {
+                ENGINE_SET_EVENT(p, ICMPV6_UNKNOWN_CODE);
+            }
+            break;
         case ND_NEIGHBOR_ADVERT:
             SCLogDebug("ND_NEIGHBOR_ADVERT");
+            if (p->icmpv6h->code != 0) {
+                ENGINE_SET_EVENT(p, ICMPV6_UNKNOWN_CODE);
+            }
+            break;
         case ND_REDIRECT:
             SCLogDebug("ND_REDIRECT");
-
             if (p->icmpv6h->code != 0) {
                 ENGINE_SET_EVENT(p, ICMPV6_UNKNOWN_CODE);
             }
-
             break;
         default:
             SCLogDebug("ICMPV6 Message type %" PRIu8 " not "