config: Update documentation for XTS option
The XTS configuration option MBEDTLS_CIPHER_MODE_XTS currently only enables
XTS for AES. So, don't say it enables XTS for "symmetric ciphers", just
AES. This helps to avoid being misleading.
/**
* \def MBEDTLS_CIPHER_MODE_XTS
*
- * Enable Xor-encrypt-xor with ciphertext stealing mode (XTS) for symmetric
- * ciphers.
+ * Enable Xor-encrypt-xor with ciphertext stealing mode (XTS) for AES.
*/
#define MBEDTLS_CIPHER_MODE_XTS
