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.)
  */