efi: Set Variable Runtime implementation

[Shantur Rathore]

Hi Heinrich,

I am trying to work out how to enable the SetVariableRT service in
U-Boot and came across your patch [1] which initially had the
SetVariable RT service enabled in EFI but in the final patch this was
removed.
I am hoping to implement it on top of the SPI Flash EFI store [2] to
be able to set Boot order and boot items from Linux the UEFI way.

Can I pick your brain on why it was dropped in the patch?
Is there any limitation in SetVariableRT service ?

Kind regards,
Shantur

[1] : https://patches.linaro.org/project/u-boot/patch/20200331060541.4212-1-xypron.glpk@gmx.de/
[2] : https://patchwork.ozlabs.org/project/uboot/list/?series=383699