flash-ipmi: implement flashHashFinish

Change-Id: I44ff6494064c11071cc9e71402e5eebab8a6a1de
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/flash-ipmi.cpp b/flash-ipmi.cpp
index 8fc9a52..dda9580 100644
--- a/flash-ipmi.cpp
+++ b/flash-ipmi.cpp
@@ -176,7 +176,12 @@
 
 bool FlashUpdate::hashFinish()
 {
-    /* TODO: implement. */
+    if (hashFd)
+    {
+        closeFile(&hashFd);
+        return true;
+    }
+
     return false;
 }