MdeModulePkg: Fix comparison with wider widths

https://codeql.github.com/codeql-query-help/cpp/cpp-comparison-with-wider-type

If the narrow type (smaller range) is compared against a wide type
(larger range), the narrow value may overflow before reaching the wide
value. This can cause unexpected behavior, such as:

Infinite loops (loop condition never becomes false).
Incorrect logic (comparison results are misleading).

Signed-off-by: Aaron Pop <aaronpop@microsoft.com>