tls: psa_pake: enforce not empty passwords

Signed-off-by: Valerio Setti <vsetti@baylibre.com>
diff --git a/include/mbedtls/ecjpake.h b/include/mbedtls/ecjpake.h
index e7ca1b2..3dd3361 100644
--- a/include/mbedtls/ecjpake.h
+++ b/include/mbedtls/ecjpake.h
@@ -113,7 +113,7 @@
  * \param curve     The identifier of the elliptic curve to use,
  *                  for example #MBEDTLS_ECP_DP_SECP256R1.
  * \param secret    The pre-shared secret (passphrase). This must be
- *                  a readable buffer of length \p len Bytes. It need
+ *                  a readable not empty buffer of length \p len Bytes. It need
  *                  only be valid for the duration of this call.
  * \param len       The length of the pre-shared secret \p secret.
  *