Features
   * Partial implementation of the PSA crypto driver interface: Mbed TLS can
     now use an external random generator instead of the library's own
     entropy collection and DRBG code. Enable MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG
     and See the documentatio of mbedtls_psa_external_get_random() for details.
   * Applications using PSA crypto can now use its random generator in the
     mbedtls_xxx API. See the documentation of mbedtls_psa_get_random() for
     details.