data tree CHANGE prepare updated validation flags

Except LYD_OPT_VAL_DATA_ONLY, none are implemented, only defined.
Operations (RPC/action/rpc-reply/notification) cannot be parsed
nor validated as they will have a separate function implemented.
Also, mandatory validation implemented.
diff --git a/src/tree_data_internal.h b/src/tree_data_internal.h
index 2c6dd4c..60afdf6 100644
--- a/src/tree_data_internal.h
+++ b/src/tree_data_internal.h
@@ -28,24 +28,6 @@
 struct lyd_node **lyd_node_children_p(struct lyd_node *node);
 
 /**
- * @brief Check validity of data parser options.
- *
- * @param ctx libyang context
- * @param options Data parser options to check
- * @param func name of the function where called
- * @return LY_SUCCESS when options are ok
- * @return LY_EINVAL when multiple data types bits are set, or incompatible options are used together.
- */
-LY_ERR lyd_parse_options_check(struct ly_ctx *ctx, int options, const char *func);
-
-/**
- * @brief Get string describing the type of the data according to the data parser options.
- * @param[in] options Data parser options to examine.
- * @return String description of the data set type.
- */
-const char *lyd_parse_options_type2str(int options);
-
-/**
  * @brief Validate, canonize and store the given @p value into the node according to the node's type's rules.
  *
  * @param[in] node Data node for the @p value.
@@ -93,14 +75,10 @@
  * @param[in] ctx libyang context
  * @param[in] data Pointer to the XML string representation of the YANG data to parse.
  * @param[in] options @ref dataparseroptions
- * @param[in] trees ([Sized array](@ref sizedarrays)) of data trees (e.g. when validating RPC/Notification) where the required
- *            data instances (leafref target, instance-identifier, when, must) can be placed. To simply prepare this structure,
- *            use lyd_trees_new(). In case of parsing RPC/action reply (LYD_OPT_RPCREPLY), the first tree in the array MUST be
- *            complete RPC/action data tree (the source request) for the reply.
  * @param[out] result Resulting list of the parsed data trees. Note that NULL can be a valid result.
  * @reutn LY_ERR value.
  */
-LY_ERR lyd_parse_xml(struct ly_ctx *ctx, const char *data, int options, const struct lyd_node **trees, struct lyd_node **result);
+LY_ERR lyd_parse_xml(struct ly_ctx *ctx, const char *data, int options, struct lyd_node **result);
 
 /**
  * @defgroup datahash Data nodes hash manipulation