Remove unused MBEDTLS_ERR_SSL_PEER_VERIFY_FAILED

The SSL error code MBEDTLS_ERR_SSL_PEER_VERIFY_FAILED is unused.

Remove it for Mbed TLS 3.0.

The code being unused comes as a surprise, at is seems to be
reasonable to report it to the user upon peer CRT verification
failure. However, this study (can potentially re-introduction
of the code) can be left for 3.x, while the error code removal
can only happen in 3.0.

Signed-off-by: Hanno Becker <hanno.becker@arm.com>
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 6b42b22..5916927 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -107,7 +107,8 @@
  * SSL       5   2 (Started from 0x5F00)
  * CIPHER    6   8 (Started from 0x6080)
  * SSL       6   24 (Started from top, plus 0x6000)
- * SSL       7   31 (Started from 0x7080, gap at 0x7300)
+ * SSL       7   30 (Started from 0x7080, gaps at
+ *                   0x7300, 0x7800)
  *
  * Module dependent error code (5 bits 0x.00.-0x.F8.)
  */
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index aaddd7f..2dd6cc4 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -77,7 +77,7 @@
 #define MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED                 -0x7680  /**< No CA Chain is set, but required to operate. */
 #define MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE                -0x7700  /**< An unexpected message was received from our peer. */
 #define MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE               -0x7780  /**< A fatal alert message was received from our peer. */
-#define MBEDTLS_ERR_SSL_PEER_VERIFY_FAILED                -0x7800  /**< Verification of our peer failed. */
+/* NOTE: Error space gap */
 #define MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY                 -0x7880  /**< The peer notified us that the connection is going to be closed. */
 #define MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO               -0x7900  /**< Processing of the ClientHello handshake message failed. */
 #define MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO               -0x7980  /**< Processing of the ServerHello handshake message failed. */