doxygen: remove unnecessary description

Due to the nature of CTR, there is no mode parameter.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
diff --git a/include/mbedtls/aria.h b/include/mbedtls/aria.h
index 9856a1c..d307ff9 100644
--- a/include/mbedtls/aria.h
+++ b/include/mbedtls/aria.h
@@ -274,10 +274,6 @@
  * \brief      This function performs an ARIA-CTR encryption or decryption
  *             operation.
  *
- *             This function performs the operation defined in the \p mode
- *             parameter (encrypt/decrypt), on the input data buffer
- *             defined in the \p input parameter.
- *
  *             Due to the nature of CTR, you must use the same key schedule
  *             for both encryption and decryption operations. Therefore, you
  *             must use the context initialized with mbedtls_aria_setkey_enc()