DynamicTablesPkg: DynamicPlatRepoLib: Fix incorrect dereferencing

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3996

The content of token should be derived from the data section of the
`CmObject` instead of the object itself.

This change fixed the issue by dereferencing the token value from the
data buffer of input CmObject.

Cc: Sami Mujawar <Sami.Mujawar@arm.com>
Cc: Alexei Fedorov <Alexei.Fedorov@arm.com>

Co-authored-by: Joe Lopez <joelopez@microsoft.com>
Signed-off-by: Kun Qin <kuqin12@gmail.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
Tested-by: Sami Mujawar <sami.mujawar@arm.com>

DynamicTablesPkg/Library/Common/DynamicPlatRepoLib/CmObjectTokenFixer.c

@@ -60,7 +60,7 @@ TokenFixerItsGroup (
   )
 {
   ASSERT (CmObject != NULL);
-  ((CM_ARM_ITS_GROUP_NODE *)CmObject)->Token = Token;
+  ((CM_ARM_ITS_GROUP_NODE *)CmObject->Data)->Token = Token;
   return EFI_SUCCESS;
 }