u-boot: fit: add support to decrypt fit with aes

This commit add to u-boot the support to decrypt
fit image encrypted with aes. The FIT image contains
the key name and the IV name. Then u-boot look for
the key and IV in his device tree and decrypt images
before moving to the next stage.

Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>
diff --git a/include/u-boot/aes.h b/include/u-boot/aes.h
index 4fb2cb7..3228104 100644
--- a/include/u-boot/aes.h
+++ b/include/u-boot/aes.h
@@ -28,4 +28,17 @@
 }
 #endif /* IMAGE_ENABLE_ENCRYPT */
 
+#if IMAGE_ENABLE_DECRYPT
+int image_aes_decrypt(struct image_cipher_info *info,
+		      const void *cipher, size_t cipher_len,
+		      void **data, size_t *size);
+#else
+int image_aes_decrypt(struct image_cipher_info *info,
+		      const void *cipher, size_t cipher_len,
+		      void **data, size_t *size)
+{
+	return -ENXIO;
+}
+#endif /* IMAGE_ENABLE_DECRYPT */
+
 #endif