Features:
+* sd-stub/sd-boot: write RNG seed to LINUX_EFI_RANDOM_SEED_TABLE_GUID config
+ table as well. (and possibly drop our efi var). Current kernels will pick up
+ the seed from there already, if EFI_RNG_PROTOCOL is not implemented by
+ firmware.
+
* sd-stub: invoke random seed logic the same way as in sd-boot, except if
random seed EFI variable is already set. That way, the variable set will be
set in all cases: if you just use sd-stub, or just sd-boot, or both.