Correct some TLS alerts and error codes

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>

library/ssl_cli.c

diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index d588fcd..e3c1ef6 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -1533,8 +1533,8 @@
         mbedtls_ssl_send_alert_message(
             ssl,
             MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
-        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
     }
 
     ((void) buf);
@@ -1558,8 +1558,8 @@
         mbedtls_ssl_send_alert_message(
             ssl,
             MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
-        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
     }
 
     ((void) buf);
@@ -1665,8 +1665,8 @@
         mbedtls_ssl_send_alert_message(
             ssl,
             MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-            MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
-        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+            MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT );
+        return( MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION );
     }
 
     /*
@@ -3031,8 +3031,8 @@
             mbedtls_ssl_send_alert_message(
                 ssl,
                 MBEDTLS_SSL_ALERT_LEVEL_FATAL,
-                MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR );
-            return( MBEDTLS_ERR_SSL_DECODE_ERROR );
+                MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER );
+            return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
         }
     }
     else