Thanks that fixed it in Windows at least. Just as a side note and maybe the reason why there are 12 pages on this. None of the mentioned solutions seems to work for this card. As I found out from other threads now, it seems to depend even on the subversion etc.
It is possible to activate it but it will slow down the system and make it unusable.
Applying the workaround proposed in another thread to use AirportBrcmFixup and brcmfx-driver=1 for some reason does not work. It will not boot.
Either I get AirPort_Brcm43xx start failed, Memory leak of bytes 116, Failed 'startGated()' or kext stall or an underrun or a kernel panic.
I read about masking pins but I really don´t like the idea.