rk3399 issue: no DMA in Linux with mainline TF-A and U-Boot SPL

[Christoph Fritz]

> 
>      The ARM PL330 DMA driver in kernel only relate to:
> 
> - DTS kernel used, can be check in /proc/device-tree/
> 
> - kernel driver which should mach the compatible name.

drivers/dma/pl330.c needs also a successfully matched amba, but this
fails when using mainline TF-A and U-Boot SPL.

I'm using the same kernel and devicetree on both tests, the only thing
changed is TF-A and U-Boot SPL   vs   mini-loader and rk3399_bl31.

> This driver should has nothing to do with U-Boot SPL or TF-A, because we 
> don't have any special setting for PL330 in loader stage.

It is drivers/amba/bus.c, which is unable to find an AMBA_CID on the
ARM bus. The DMA driver not loading is just a symptom of this issue.

Any ideas?

Thanks
  -- Christoph