This worked.
1) Download the install AMD Radeon Windows 10 drivers that were released couple of days ago. 15.7.1 I believe.
2) After installing rebooting, go to regedit. In regedit, go to the Find option in the Edit Menu.
3) Search for EnableULPS. Double click on it and change the value from 1 to 0.
4) Exit regedit and restart your laptop.
Now with both cards enabled, the laptop boots and wakes as before nice and quickly.
Charles
October 2015