Restructured cipher_set_padding_mode() to use switch statement
diff --git a/include/polarssl/cipher.h b/include/polarssl/cipher.h
index 7ee17ab..13d714b 100644
--- a/include/polarssl/cipher.h
+++ b/include/polarssl/cipher.h
@@ -417,8 +417,10 @@
* \param ctx generic cipher context
* \param mode padding mode
*
- * \returns 0 on success, POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
- * if parameters verification fails.
+ * \returns 0 on success, POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE
+ * if selected padding mode is not supported, or
+ * POLARSSL_ERR_CIPHER_BAD_INPUT_DATA if the cipher mode
+ * does not support padding.
*/
int cipher_set_padding_mode( cipher_context_t *ctx, cipher_padding_t mode );