b43: Prepare driver for sleeping busses

This patchset is the first series to remove atomic sections from the b43 driver to allow running b43 on a slow bus like SDIO that needs to sleep for register accesses.

Greetings, Michael.

I have installed this patch set and find no problems. It compiles correctly after each step is installed, which ensures proper bisection. The code appears to work correctly.

I also tested the stand-alone version of interrupt threading without problems.