[U-Boot] [PATCH v3] at91: Add arch_preboot_os which disables PIT in a faster way

[Reinhard Meyer]

Dear Alexander Stein,
> When disabled the PIT runs until it reaches the CPIV value.
> The Linux PIT driver stops the PIT and waits until it stopped. This can
> take over 100ms. Simply stopping in u-boot isn't sufficient as the PIT
> will still be running when Linux is waiting until it stopped.
> So, we stop it in u-boot by setting the compare value to a value slightly
> greater than the current running counter to make the PIT stopped in short
> time.
> 
> Signed-off-by: Alexander Stein <alexander.stein at systec-electronic.com>
> ---
> 
> Changes in v3:
> * Really fix comment

Applied to u-boot-atmel/at91.

Thanks,
Reinhard