fix: Treat Document Links entries as all non-std fields

- Since the field name is specified use it as a non standard field because it is hard to determine which field is standard. It is often wrong to assume the first entry has the statndard field

(cherry picked from commit d412972)

frappe/model/meta.py

@@ -694,15 +694,12 @@ def add_doctype_links(self, data):
 					dict(label=link.group, items=[link.parent_doctype or link.link_doctype])
 				)
 
+			if not data.fieldname and link.link_fieldname:
+				data.fieldname = link.link_fieldname
+
 			if not link.is_child_table:
-				if link.link_fieldname != data.fieldname:
-					if data.fieldname:
-						data.non_standard_fieldnames[link.link_doctype] = link.link_fieldname
-					else:
-						data.fieldname = link.link_fieldname
+				data.non_standard_fieldnames[link.link_doctype] = link.link_fieldname
 			elif link.is_child_table:
-				if not data.fieldname:
-					data.fieldname = link.link_fieldname
 				data.internal_links[link.parent_doctype] = [link.table_fieldname, link.link_fieldname]
 
 	def get_row_template(self):