CometlakeOpenBoardPkg: Fix build error due to Ddr4MixedUDimm2DpcLimit

The Ddr4MixedUDimm2DpcLimit FSP-M Upd has been renamed as
Ddr4Mixed2DpcLimit at CometLakeFspBinPkg\CometLake1.
FSP wrapper driver need to use FSP-M Upd name Ddr4Mixed2DpcLimit
from CometLake1 FSP at CometlakeOpenBoardPkg.

REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2714



Signed-off-by: Kathappan Esakkithevar <kathappan.esakkithevar@intel.com>
Cc: Sai Chaganty <rangasai.v.chaganty@intel.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Nate DeSimone <nathaniel.l.desimone@intel.com>
Cc: Deepika Kethi Reddy <deepika.kethi.reddy@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Sai Chaganty <rangasai.v.chaganty@intel.com>
Reviewed-by: Eric Dong <eric.dong@intel.com>