fixup! Add a convenient libflashrom interface

The buffer passed to flashrom_image_write() isn't `const`. It might be
altered for full verification (with mixed contents if a layout is being
used).

Change-Id: Ibd8a9579e5dd859ae03b0deb3042b7035719e5de
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/20266
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: David Hendricks <david.hendricks@gmail.com>
diff --git a/flashrom.c b/flashrom.c
index 503a199..838dfd0 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -2294,7 +2294,7 @@
  * containing included regions will be touched.
  *
  * @param flashctx The context of the flash chip.
- * @param buffer Source buffer to read image from.
+ * @param buffer Source buffer to read image from (may be altered for full verification).
  * @param buffer_len Size of source buffer in bytes.
  * @return 0 on success,
  *         4 if buffer_len doesn't match the size of the flash chip,