Remove mbedtls_low_level_sterr() and mbedtls_high_level_strerr()

Just removed from the API. We can greatly simplify error.c but that will be
for later.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/ChangeLog.d/error-unification.txt b/ChangeLog.d/error-unification.txt
index e1790d2..a19e60c 100644
--- a/ChangeLog.d/error-unification.txt
+++ b/ChangeLog.d/error-unification.txt
@@ -5,3 +5,7 @@
      Mbed TLS error codes..
      This will not affect most applications since in both cases, the
      error values are between -32767 and -1 as before.
+
+Removals
+   * Remove mbedtls_low_level_sterr() and mbedtls_high_level_strerr(),
+     since these concepts no longer exists. There is just mbedtls_strerror().
diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 8b7c19a..7abb00f 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -30,36 +30,6 @@
  */
 void mbedtls_strerror(int errnum, char *buffer, size_t buflen);
 
-/**
- * \brief Translate the high-level part of an Mbed TLS error code into a string
- *        representation.
- *
- * This function returns a const pointer to an un-modifiable string. The caller
- * must not try to modify the string. It is intended to be used mostly for
- * logging purposes.
- *
- * \param error_code    error code
- *
- * \return The string representation of the error code, or \c NULL if the error
- *         code is unknown.
- */
-const char *mbedtls_high_level_strerr(int error_code);
-
-/**
- * \brief Translate the low-level part of an Mbed TLS error code into a string
- *        representation.
- *
- * This function returns a const pointer to an un-modifiable string. The caller
- * must not try to modify the string. It is intended to be used mostly for
- * logging purposes.
- *
- * \param error_code    error code
- *
- * \return The string representation of the error code, or \c NULL if the error
- *         code is unknown.
- */
-const char *mbedtls_low_level_strerr(int error_code);
-
 #ifdef __cplusplus
 }
 #endif
diff --git a/scripts/data_files/error.fmt b/scripts/data_files/error.fmt
index b75a9ab..14522ec 100644
--- a/scripts/data_files/error.fmt
+++ b/scripts/data_files/error.fmt
@@ -20,7 +20,7 @@
 
 HEADER_INCLUDED
 
-const char *mbedtls_high_level_strerr(int error_code)
+static const char *mbedtls_high_level_strerr(int error_code)
 {
     int high_level_error_code;
 
@@ -43,7 +43,7 @@
     return NULL;
 }
 
-const char *mbedtls_low_level_strerr(int error_code)
+static const char *mbedtls_low_level_strerr(int error_code)
 {
     int low_level_error_code;