firmware: start implementing close method

The close method is used to indicate something is done, for instance,
uploading a firmware image or tarball.

Change-Id: I9e972ea12282e700863d51db497c6294040cd2ca
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/static_handler.cpp b/static_handler.cpp
index 8cb20e0..c4fa602 100644
--- a/static_handler.cpp
+++ b/static_handler.cpp
@@ -14,6 +14,11 @@
     return false;
 }
 
+void StaticLayoutHandler::close()
+{
+    return;
+}
+
 bool StaticLayoutHandler::write(std::uint32_t offset,
                                 const std::vector<std::uint8_t>& data)
 {