decode: fix -Wshorten-64-to-32 warnings

Ticket: #6186

src/decode-teredo.c

@@ -182,7 +182,7 @@ int DecodeTeredo(ThreadVars *tv, DecodeThreadVars *dtv, Packet *p,
 
         if (len ==  IPV6_HEADER_LEN +
                 IPV6_GET_RAW_PLEN(thdr) + (start - pkt)) {
-            int blen = len - (start - pkt);
+            uint32_t blen = len - (uint32_t)(start - pkt);
             /* spawn off tunnel packet */
             Packet *tp = PacketTunnelPktSetup(tv, dtv, p, start, blen,
                     DECODE_TUNNEL_IPV6_TEREDO);

src/decode.c

@@ -350,7 +350,7 @@ inline int PacketCopyDataOffset(Packet *p, uint32_t offset, const uint8_t *data,
  */
 inline int PacketCopyData(Packet *p, const uint8_t *pktdata, uint32_t pktlen)
 {
-    SET_PKT_LEN(p, (size_t)pktlen);
+    SET_PKT_LEN(p, pktlen);
     return PacketCopyDataOffset(p, 0, pktdata, pktlen);
 }
 
@@ -810,7 +810,7 @@ void DecodeThreadVarsFree(ThreadVars *tv, DecodeThreadVars *dtv)
  */
 inline int PacketSetData(Packet *p, const uint8_t *pktdata, uint32_t pktlen)
 {
-    SET_PKT_LEN(p, (size_t)pktlen);
+    SET_PKT_LEN(p, pktlen);
     if (unlikely(!pktdata)) {
         return -1;
     }