SPL: Add signature verification when loading image

U-boot proper signature is not verified by SPL on most platforms
even config SPL_FIT_SIGNATURE is enabled. Only fsl-layerscape
platform support secure boot in platform specific code. So
verified boot cannot be achieved if u-boot proper is loaded by
SPL.

This patch add signature verification to u-boot proper images
when loading FIT image in SPL. It is tested on Allwinner bananapi
zero board with H2+ SoC.

Signed-off-by: Jun Nie <jun.nie@linaro.org>
diff --git a/common/image-fit.c b/common/image-fit.c
index f6e956a..4b03390 100644
--- a/common/image-fit.c
+++ b/common/image-fit.c
@@ -1068,34 +1068,14 @@
 	return 0;
 }
 
-/**
- * fit_image_verify - verify data integrity
- * @fit: pointer to the FIT format image header
- * @image_noffset: component image node offset
- *
- * fit_image_verify() goes over component image hash nodes,
- * re-calculates each data hash and compares with the value stored in hash
- * node.
- *
- * returns:
- *     1, if all hashes are valid
- *     0, otherwise (or on error)
- */
-int fit_image_verify(const void *fit, int image_noffset)
+int fit_image_verify_with_data(const void *fit, int image_noffset,
+			       const void *data, size_t size)
 {
-	const void	*data;
-	size_t		size;
 	int		noffset = 0;
 	char		*err_msg = "";
 	int verify_all = 1;
 	int ret;
 
-	/* Get image data and data length */
-	if (fit_image_get_data(fit, image_noffset, &data, &size)) {
-		err_msg = "Can't get image data/size";
-		goto error;
-	}
-
 	/* Verify all required signatures */
 	if (IMAGE_ENABLE_VERIFY &&
 	    fit_image_verify_required_sigs(fit, image_noffset, data, size,
@@ -1153,6 +1133,38 @@
 }
 
 /**
+ * fit_image_verify - verify data integrity
+ * @fit: pointer to the FIT format image header
+ * @image_noffset: component image node offset
+ *
+ * fit_image_verify() goes over component image hash nodes,
+ * re-calculates each data hash and compares with the value stored in hash
+ * node.
+ *
+ * returns:
+ *     1, if all hashes are valid
+ *     0, otherwise (or on error)
+ */
+int fit_image_verify(const void *fit, int image_noffset)
+{
+	const void	*data;
+	size_t		size;
+	int		noffset = 0;
+	char		*err_msg = "";
+
+	/* Get image data and data length */
+	if (fit_image_get_data(fit, image_noffset, &data, &size)) {
+		err_msg = "Can't get image data/size";
+		printf("error!\n%s for '%s' hash node in '%s' image node\n",
+		       err_msg, fit_get_name(fit, noffset, NULL),
+		       fit_get_name(fit, image_noffset, NULL));
+		return 0;
+	}
+
+	return fit_image_verify_with_data(fit, image_noffset, data, size);
+}
+
+/**
  * fit_all_image_verify - verify data integrity for all images
  * @fit: pointer to the FIT format image header
  *