Add CONFIG_TPM_NO_LUKS_DISK_UNLOCK to allow Librem boards to opt
out of using TPM to store LUKS key, and use it to guard the user
option to add the disk encryption key to the TPM.
Select this option for all Librem boards; all other boards which
select CONFIG_TPM=y will have no change in functionality.
Signed-off-by: Matt DeVillier <matt.devillier@puri.sm>