Add common feature unavailable error
Add a common error for the feature unavailable, in the
platform module.
diff --git a/include/mbedtls/platform.h b/include/mbedtls/platform.h
index 5cd143c..89fe8a7 100644
--- a/include/mbedtls/platform.h
+++ b/include/mbedtls/platform.h
@@ -43,7 +43,8 @@
#include "platform_time.h"
#endif
-#define MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED -0x0070 /**< Hardware accelerator failed */
+#define MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED -0x0070 /**< Hardware accelerator failed */
+#define MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED -0x0072 /**< The requested feature is not supported by the platform */
#ifdef __cplusplus
extern "C" {