board: gateworks: venice: gsc: fix voltage offset

The voltage offset property is in microvolts so must be scaled
accordingly.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
diff --git a/board/gateworks/venice/gsc.c b/board/gateworks/venice/gsc.c
index 23ad580..9a6712e 100644
--- a/board/gateworks/venice/gsc.c
+++ b/board/gateworks/venice/gsc.c
@@ -298,7 +298,7 @@
 				}
 
 				/* adjust by offset */
-				val += offset;
+				val += (offset / 1000);
 
 				printf("%-8s: %d.%03dV\n", label, val / 1000, val % 1000);
 				break;