Introduce MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE error code

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 9d48c9a..479a63e 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -101,10 +101,9 @@
  * HKDF      5   1 (Started from top)
  * SSL       5   2 (Started from 0x5F00)
  * CIPHER    6   8 (Started from 0x6080)
- * SSL       6   23 (Started from top, plus 0x6000, gaps at
- *                   0x6E00)
  * SSL       7   30 (Started from 0x7080, gaps at
  *                   0x7500, 0x7580)
+ * SSL       6   24 (Started from top, plus 0x6000)
  *
  * Module dependent error code (5 bits 0x.00.-0x.F8.)
  */
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index df6b629..728b546 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -96,7 +96,7 @@
 #define MBEDTLS_ERR_SSL_HW_ACCEL_FAILED                   -0x7F80  /**< Hardware acceleration function returned with error */
 #define MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH              -0x6F80  /**< Hardware acceleration function skipped / left alone data */
 #define MBEDTLS_ERR_SSL_BAD_PROTOCOL_VERSION              -0x6E80  /**< Handshake protocol not within min/max boundaries */
-/* Error space gap */
+#define MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE                 -0x6E00  /**< Handshake negotiation failed because of incompatible parameter sets supported by client and server. */
 #define MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED            -0x6D80  /**< Session ticket has expired. */
 #define MBEDTLS_ERR_SSL_PK_TYPE_MISMATCH                  -0x6D00  /**< Public key type mismatch (eg, asked for RSA key exchange and presented EC key) */
 #define MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY                  -0x6C80  /**< Unknown identity received (eg, PSK identity) */