Provide mask_param() function to uniformly mask secret parameters,
while still indicating whether they are empty.
Extend DO_WITH_DEBUG to allow masking a password parameter by position,
using mask_param(). Move from ash_functions to functions (isn't used
by ash scripts).
Mask password parameters in kexec-unseal-key and tpmr seal. Use
mask_param() on existing masked params in tpmr.
Trim more troubleshooting output from tpm2_extend() in tpmr.
Clarify tpmr kexec_finalize echo; it's the TPM's platform heirarchy,
users might not know what this was referring to.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>