[U-Boot] [RFC v2] env: Fix errors printing on env loading

[Wolfgang Denk]

Dear Sam Protsenko,

In message <20180719193028.814-1-semen.protsenko at linaro.org> you wrote:
> This is just a draft to discuss ideas related to "Make U-Boot log great
> again" thread.
>
> With this patch we will have something like this:
>
>     Attempting to load environment from FAT:
>       -> MMC: no card present
>       -> ** Bad device mmc 0 **
>       -> Failed (-5)
>     Attempting to load environment from MMC: OK
>
> instead of this:
>
>     Loading Environment from FAT... MMC: no card present
>     ** Bad device mmc 0 **
>     Failed (-5)
>     Loading Environment from MMC... OK
>
> Two things were done in this patch:
>  - print messages from drivers in nested style (with "->" prefix); to do
>    so, add GD_FLG_PR_PREFIX flag and check it in puts()
>  - make "OK" to be printed on the same line as main message; to do so,
>    issue ASCII escape codes [1] to move cursor back to main message line

Naked-by: Wolfgang Denk <wd at denx.de>

Best regards,

Wolfgang Denk

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