[U-Boot] FDT driver initialization function declaration

[Marek Vasut <marex@denx.de>]

Dear Wolfgang Denk,

> Dear Michal Simek,
> 
> In message <4FFC1EF8.9060705@monstr.eu> you wrote:
> > The hardest part I have identify on microblaze was about u-boot
> > variables. Because based on information from device-tree you can choose
> > where variables should be stored and also this memory should be
> > accessible before u-boot try to read variables. It mean in very early
> > state.
> 
> Device initialization before relocation is already hard enough;

+1

> resources are very limited then.

And we'll be introducing the early mallocator. This is where MPC85x will blow my 
mind :) (I'm repeating myself here, but it might help getting others unaware of 
the DM work better in line).

> You will add the additional need to
> have the FDT library available then, too.   Not to mention that you
> need to load the DT blob, too.

DT blob can be read from ROM if that was the problem. The DT library and parser 
might be an issue.

> This will be a lot of added complexity.

And therefore slowing down the boot. But I believe it can be optimized to 
leverage this to some point. Though I'm not quite sure how much. This is worthy 
investigation.

Michal, can you try investigating how will the DT probing intertwine with the 
DM?

> Best regards,
> 
> Wolfgang Denk

Best regards,
Marek Vasut