[Buildroot] Patches for Acme Systems Arietta G25 and Aria G25

[Biagio Montaruli]

Hi Buildroot developers and maintainers,
first of all I would like to thank you for all the work that you make everyday
to improve Buildroot, then I would submit my patches to improve Buildroot 
configuration for Acme Systems Arietta G25 and Aria G25. 
I have improved and updated AT91bootstrap, the kernel and genimage
configuration in order to make a bootable SD card image.
If you find some problems or mistakes in patches I have sent to you and if you  
want to give me some suggestions about my work, please send me an email :
your advices are always welcome !

Best regards and have a good day,
Biagio.