FRANKFURT (Reuters) – Siemens Energy is in constructive talks with Spain’s stock market supervisor on a planned takeover bid for Siemens Gamesa, the company said, but added it could not say when a required approval for the deal would be obtained. Siemens Energy in May unveiled plans to buy the remaining third in Siemens Gamesa it does not already own for 4.05 billion euros ($3.99 billion), a plan that needs to be approved by Spanish regulator CNMV. Under a tentative timeline Siemens Energy previously said that the bid would launch in mid-September. “We cannot comment on the timing of the Spani…