[U-Boot] [PATCH] powerpc/913x: Add config flag for bootdelay

[Harninder Rai]

> 
> The change is trivial. Do you mind to explain why you need this change?
Thanks for the review. This change is required to give user some time to interrupt the booting process
Also, this will allow the system to boot from flash after power-on (does help in automation testing)
Is this sufficient for a commit message?

Harry++
> 
> York