dummyflasher: const-correct and fix print fmt

Re-sync with upstream by bringing in const-correctness and printer
formatting fixes. Also align function prototypes with upstreams
line wrapping.

No logic changes.

BUG=b:151572799
BRANCH=none
TEST=emerge-(chell|daisy) sys-apps/flashrom still builds

Signed-off-by: Stuart Langley <slangley@chromium.org>
Change-Id: I073e13ce5f3e617827e49a78776c6cb6e730f5de
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashrom/+/2121001
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
diff --git a/programmer.c b/programmer.c
index a36102e..cc4ebad 100644
--- a/programmer.c
+++ b/programmer.c
@@ -99,7 +99,7 @@
 	return val;
 }
 
-void fallback_chip_writen(const struct flashctx *flash, uint8_t *buf, chipaddr addr, size_t len)
+void fallback_chip_writen(const struct flashctx *flash, const uint8_t *buf, chipaddr addr, size_t len)
 {
 	size_t i;
 	for (i = 0; i < len; i++)