bootutil: Add TLV for correct ED25519 usage

The pure ED25519 TLV has stores ED25519 signature over SHA512 of
image, rather than signature over SHA512 of SHA256 of image.

Signed-off-by: Dominik Ermel <[email protected]>

boot/bootutil/include/bootutil/image.h

@@ -94,6 +94,7 @@ struct flash_area;
 #define IMAGE_TLV_ECDSA_SIG         0x22   /* ECDSA of hash output */
 #define IMAGE_TLV_RSA3072_PSS       0x23   /* RSA3072 of hash output */
 #define IMAGE_TLV_ED25519           0x24   /* ed25519 of hash output */
+#define IMAGE_TLV_ED25519_PURE      0x25   /* ed25519 over SHA512 of the image */
 #define IMAGE_TLV_ENC_RSA2048       0x30   /* Key encrypted with RSA-OAEP-2048 */
 #define IMAGE_TLV_ENC_KW            0x31   /* Key encrypted with AES-KW 128 or 256*/
 #define IMAGE_TLV_ENC_EC256         0x32   /* Key encrypted with ECIES-EC256 */