fsl_etsec: Fix various small problems in hexdump code

Fix various small problems in hexdump code, such as:
    - Reference to non-existing field etsec->nic->nc.name is replaced
    with nc->name

    - Type mismatch warnings
Signed-off-by: NAndrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>

hw/net/fsl_etsec/etsec.c

@@ -348,8 +348,8 @@ static ssize_t etsec_receive(NetClientState *nc,
     eTSEC *etsec = qemu_get_nic_opaque(nc);
 
 #if defined(HEX_DUMP)
-    fprintf(stderr, "%s receive size:%d\n", etsec->nic->nc.name, size);
-    qemu_hexdump(buf, stderr, "", size);
+    fprintf(stderr, "%s receive size:%zd\n", nc->name, size);
+    qemu_hexdump((void *)buf, stderr, "", size);
 #endif
     /* Flush is unnecessary as are already in receiving path */
     etsec->need_flush = false;