Previously, the GPT device GUID was being used instead of the partition,
which was incorrect.
Signed-off-by: Alfonso Sánchez-Beato <alfonso.sanchez-beato@canonical.com>
Let EFI_LOADER select CONFIG_PARTITION_UUIDS.
Use log_warning() instead of printf() for warning.
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>