Add output to pcr allocate to ask for TPM reset

[heike380]

By creating this pull request you agree to the terms in CONTRIBUTING.md.
https://github.com/Infineon/.github/blob/master/CONTRIBUTING.md
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Add a comment to the output of pcr allocate to remember the user to perform a TPM reset.
e.g. output of eltt2 -l sha1 looks now like that:

PCR allocate SHA-1 bank.
In order to take effect, please perform a TPM reset.
Done.