Deprecate hardware acceleration errors
Deprecate the module-specific XXX_HW_ACCEL_FAILED and
XXX_FEATURE_UNAVAILABLE errors, as alternative implementations should now
return `MBEDTLS_ERR_PLATFORM_HW_FAILED` and
`MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED`.
diff --git a/include/mbedtls/des.h b/include/mbedtls/des.h
index 91d16b6..d62042d 100644
--- a/include/mbedtls/des.h
+++ b/include/mbedtls/des.h
@@ -42,6 +42,8 @@
#define MBEDTLS_DES_DECRYPT 0
#define MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH -0x0032 /**< The data input has an invalid length. */
+
+/* MBEDTLS_ERR_DES_HW_ACCEL_FAILED is deprecated and should not be used. */
#define MBEDTLS_ERR_DES_HW_ACCEL_FAILED -0x0033 /**< DES hardware accelerator failed. */
#define MBEDTLS_DES_KEY_SIZE 8