Suggest using /dev/tpmrm0 over /dev/tpm

[wiktor-k]

Parsec by default is using /dev/tpm which provides a low-level access to the TPM. This is problematic for several reasons: /dev/tpm can be accessed only by one client at a time since it doesn't provide a resource manager.

It would be better if the documentation suggested using /dev/tpmrm0 over /dev/tpm. /dev/tpmrm0 can be accessed by multiple clients since it uses in kernel Resource Manager. /dev/tpmrm0 additionally is more accessible than /dev/tpm in most distros since /dev/tpmrm0 requires membership in the tss group while /dev/tpm is accessible only by root.

As @paulhowardarm noticed the default cannot be changed since it would be a breaking change.

Suggested change: in docs prefer /dev/tpmrm0 over /dev/tpm and note that the parsec user need to be added to the tss group.