Get rid of the "Could not initialize TCTI file: libtss2-tcti" message in the initrd on secure boot systems

[mtoman]

When the cryptsetup initrd script decrypts the LUKS passphrase using the TPM, it spits out error messages, e.g.

ERROR:tcti:../tpm2-tss-3.2.0/src/tss2-tcti/tctildr-dl.c:154:tcti_from_file() Could not initialize TCTI file: libtss2-tcti

This is harmless, it just does not look good - there are multiple backends that tpm2-tools use to talk to the TPM (directly via /dev/tpmXXX, via abrmd, via libtss). We only support the first option but tpm2-tools will iterate through all of them and use the first one that works. Some ideas to get rid of the message are:

• See if we can compile --without tss and --without abrmd
• See if we can change the order in which the methods are tried making the direct access first
• Always enforce /dev/tpmrm0 in the script by setting the env var TPM2TOOLS_TCTI="device:/dev/tpmrm0". This is what flasher does: https://github.com/balena-os/meta-balena/blob/master/meta-balena-common/recipes-support/resin-init/resin-init-flasher/resin-init-flasher#L269
• ... something else