ClevoOpenBoardPkg: Fix duplicate GUID in DSC

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2064



Assigns a unique GUID to PLATFORM_GUID.

Cc: Ankit Sinha <ankit.sinha@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Michael Kubacki <michael.a.kubacki@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>