Validator: simplify (and correct) the map sorting verification

We don't need to compare the map lengths directly. The memcmp is
sufficient, since the source data is big endian.

Of course, verifying for sorting requires the map has known length.

Signed-off-by: Thiago Macieira <thiago.macieira@intel.com>

src/cborvalidation.c

@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2019 Intel Corporation
+** Copyright (C) 2021 Intel Corporation
 **
 ** Permission is hereby granted, free of charge, to any person obtaining a copy
 ** of this software and associated documentation files (the "Software"), to deal