DynamicTablesPkg: Update error handling for node creation

The node creation functions:
- AmlCreateRootNode()
- AmlCreateObjectNode()
- AmlCreateDataNode()
are now resetting the input pointer where the created node is stored.
Thus, it is not necessary to set some local variables to NULL or
check a node value before trying to delete it.

Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>

DynamicTablesPkg/Library/Common/AmlLib/CodeGen/AmlCodeGen.c

@@ -148,7 +148,6 @@ AmlCodeGenString (
     return EFI_INVALID_PARAMETER;
   }
 
-  ObjectNode = NULL;
   DataNode = NULL;
 
   Status = AmlCreateObjectNode (
@@ -187,10 +186,7 @@ AmlCodeGenString (
   return Status;
 
 error_handler:
-  if (ObjectNode != NULL) {
-    AmlDeleteTree ((AML_NODE_HEADER*)ObjectNode);
-  }
-
+  AmlDeleteTree ((AML_NODE_HEADER*)ObjectNode);
   return Status;
 }
 

DynamicTablesPkg/Library/Common/AmlLib/Tree/AmlClone.c

@@ -43,8 +43,6 @@ AmlCloneNode (
     return EFI_INVALID_PARAMETER;
   }
 
-  *ClonedNode = NULL;
-
   if (IS_AML_DATA_NODE (Node)) {
     DataNode = (AML_DATA_NODE*)Node;
     Status = AmlCreateDataNode (