ESYS: Fix conversion of gcrypt mpi numbers to binary data.
ESYS: Fix conversion of gcrypt mpi numbers to binary data.

* Fixed sizes for the binary data are now used in all cases.
* Variable sizes caused race conditions in RSA encryption and
  ECDH key exchange:
    * TPM decryption with OAEP failed in rare cases when the cipher size
      computed by gcry_mpi_print is lower than the key size
      (With openSSL and gcrypt it's possible to decrypt such ciphers).
    * The computation of the shared secret failed in rare cases when the
      size of the x coordinate of the product Q*d  computed by
      gcry_mpi_print(in function iesys_cryptogcry_get_ecdh_point)
      is lower than the maximum size of a point coordinate.

Signed-off-by: Juergen Repp <e8766a256249b38ef00a5278093d688d4ec9536d@sit.fraunhofer.de>

01org/tpm2-tss,tpm2-software/tpm2-tss,01org/tpm2-tss,01org/TPM2.0-TSS,01org/tpm2-tss,01org/TPM2.0-TSS,01org/TPM2.0-TSS,tpm2-software/tpm2-tss,01org/TPM2.0-TSS,tpm2-software/tpm2-tss