[GRUB] Adapt GRUB env. and wic partition not assigning a fixed PARTUUID
Remove GRUB environment's variable root_env_bootarg
. Let GRUB's
bootscript discover the correct root device.
Remove no-more-needed fixed PARTUUID for rootfs partition.
Signed-off-by: Nicola Sparnacci nicola.sparnacci@seco.com