#4 Fix HifiBerry DAC+ and don't compile & load on board sound

This is an update to my previous PR which I can't see here anymore :( So I created a new branch.

It's not finished! Please review the last commit (wip = work in progress). I'm able to not compile and load the snd-bcm2835 module. I can select it, and it gets compiled & loaded. Hooray!

BUT:

• I'm too stupid to make the menu take the option away. If I unselect & save, it's still in .config, and gets compiled/installed.
• the location and appearance of this one option in the top level is obviously godawful.
• in general, I wonder a bit about the option groups "Optional hardware" and "Audio Board" - they appear above the "don't touch things above here"-section, but in fact selecting/deselecting works just fine, or do I miss something here? Shouldn't they go somewhere else, maybe a special "board hardware" section or some such?

fixed it in another way.

I don't think changing the audio board will leave the config in a good state, so I am keeping it in the no change section of make menuconfig.