MinPlatformPkg: Fix duplicate GUID

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=1983



PeiLib.inf and TestPointCheckLibNull.inf currently have the same GUID.
This patch assigns a unique GUID to each library INF file.

Cc: Chasel Chiu <chasel.chiu@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: Liming Gao <liming.gao@intel.com>