tests: legacy: resolve conflict with MON defined in HAL

Some header files were defining MON and causing a conflict, so call this
something unique and avoid future conflicts.

Change-Id: If9d2553a20b3afae50a09f4c0e10733ee1cdd58d
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
2 files changed