serprog.c: Resync with upstream

Align our implementation completely with upstreams.

BUG=b:140397190
BRANCH=none
TEST=none

Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Change-Id: Ied508a054be4647c59b94bcc821a68785c3517a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashrom/+/2445982
Commit-Queue: Edward O'Callaghan <quasisec@chromium.org>
Commit-Queue: Sam McNally <sammc@chromium.org>
Tested-by: Edward O'Callaghan <quasisec@chromium.org>
Auto-Submit: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Sam McNally <sammc@chromium.org>
diff --git a/programmer.h b/programmer.h
index e0a8350..9f764b0 100644
--- a/programmer.h
+++ b/programmer.h
@@ -815,6 +815,7 @@
 #if CONFIG_SERPROG == 1
 int serprog_init(void);
 void serprog_delay(unsigned int usecs);
+void *serprog_map(const char *descr, uintptr_t phys_addr, size_t len);
 #endif
 
 /* serial.c */