agent: Fix the regression in pkdecrypt with TPM RSA.
* agent/divert-tpm2.c (divert_tpm2_pkdecrypt): Care about additional 0x00.
Cherry pick master commit of:
6eed3959303c81c9699fe9273030e480732f72be
- GnuPG-bug-id: T8045
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>