New MD API: rename functions from _ext to _ret

The _ext suffix suggests "new arguments", but the new functions have
the same arguments. Use _ret instead, to convey that the difference is
that the new functions return a value.
diff --git a/include/mbedtls/md2.h b/include/mbedtls/md2.h
index 23145de..0df6b36 100644
--- a/include/mbedtls/md2.h
+++ b/include/mbedtls/md2.h
@@ -86,7 +86,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_md2_starts_ext( mbedtls_md2_context *ctx );
+int mbedtls_md2_starts_ret( mbedtls_md2_context *ctx );
 
 /**
  * \brief          MD2 process buffer
@@ -97,7 +97,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_md2_update_ext( mbedtls_md2_context *ctx,
+int mbedtls_md2_update_ret( mbedtls_md2_context *ctx,
                             const unsigned char *input,
                             size_t ilen );
 
@@ -109,7 +109,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_md2_finish_ext( mbedtls_md2_context *ctx,
+int mbedtls_md2_finish_ret( mbedtls_md2_context *ctx,
                             unsigned char output[16] );
 
 /**
@@ -130,20 +130,20 @@
 /**
  * \brief          MD2 context setup
  *
- * \deprecated     Superseded by mbedtls_md2_starts_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_md2_starts_ret() in 2.5.0
  *
  * \param ctx      context to be initialized
  */
 MBEDTLS_DEPRECATED static inline void mbedtls_md2_starts(
                                                     mbedtls_md2_context *ctx )
 {
-    mbedtls_md2_starts_ext( ctx );
+    mbedtls_md2_starts_ret( ctx );
 }
 
 /**
  * \brief          MD2 process buffer
  *
- * \deprecated     Superseded by mbedtls_md2_update_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_md2_update_ret() in 2.5.0
  *
  * \param ctx      MD2 context
  * \param input    buffer holding the data
@@ -154,13 +154,13 @@
                                                 const unsigned char *input,
                                                 size_t ilen )
 {
-    mbedtls_md2_update_ext( ctx, input, ilen );
+    mbedtls_md2_update_ret( ctx, input, ilen );
 }
 
 /**
  * \brief          MD2 final digest
  *
- * \deprecated     Superseded by mbedtls_md2_finish_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_md2_finish_ret() in 2.5.0
  *
  * \param ctx      MD2 context
  * \param output   MD2 checksum result
@@ -169,7 +169,7 @@
                                                     mbedtls_md2_context *ctx,
                                                     unsigned char output[16] )
 {
-    mbedtls_md2_finish_ext( ctx, output );
+    mbedtls_md2_finish_ret( ctx, output );
 }
 
 /**
@@ -207,7 +207,7 @@
  * \param ilen     length of the input data
  * \param output   MD2 checksum result
  */
-int mbedtls_md2_ext( const unsigned char *input,
+int mbedtls_md2_ret( const unsigned char *input,
                      size_t ilen,
                      unsigned char output[16] );
 
@@ -220,7 +220,7 @@
 /**
  * \brief          Output = MD2( input buffer )
  *
- * \deprecated     Superseded by mbedtls_md2_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_md2_ret() in 2.5.0
  *
  * \param input    buffer holding the data
  * \param ilen     length of the input data
@@ -230,7 +230,7 @@
                                                    size_t ilen,
                                                    unsigned char output[16] )
 {
-    mbedtls_md2_ext( input, ilen, output );
+    mbedtls_md2_ret( input, ilen, output );
 }
 
 #undef MBEDTLS_DEPRECATED