pdr: Deprecate entity_association_tree_find()

entity_association_tree_find() appears to be internal function as it is
not exposed in the public headers. Motivate any users to migrate off of
it by marking it as deprecated so that it can subsequently be marked as
static.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I03eb6f424b29b39dcb79419769c6c4f70dc4650b
diff --git a/src/pdr.c b/src/pdr.c
index b8ac15f..3b30329 100644
--- a/src/pdr.c
+++ b/src/pdr.c
@@ -1165,7 +1165,7 @@
 	return node;
 }
 
-LIBPLDM_ABI_STABLE
+LIBPLDM_ABI_DEPRECATED
 void entity_association_tree_find(pldm_entity_node *node, pldm_entity *entity,
 				  pldm_entity_node **out)
 {