MCPE: Fix Dead Store (Dead assignement/Dead increment) warning found by Clang

Change-Id: I7053c3c9e42cb4246ae504d31213bf95917a34f2
Reviewed-on: https://code.wireshark.org/review/7264
Reviewed-by: Anders Broman <a.broman58@gmail.com>

epan/dissectors/packet-mcpe.c

@@ -90,7 +90,7 @@ mcpe_dissect_detail_0xA0(tvbuff_t *tvb, proto_tree *raknet_tree, gint offset)
         item_size = 3;
         proto_tree_add_item(raknet_tree, hf_mcpe_general_packet_number, tvb,
                             offset, item_size, ENC_BIG_ENDIAN);
-        offset += item_size;
+        /*offset += item_size;*/
     }
 }