Refactor of bmcImages

bmcImages were in image_verify.hpp but it is used not only in image
verification, but elsewhere.

Move it into a more generic header file, images.hpp, so it makes more
clear that users of bmcImages include images.hpp instead of
image_verify.hpp

Tested: Verify the code pass the build.

Change-Id: If9adf315eee9047d9d08ab93ed7c0ff3c97f7a1e
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/item_updater.cpp b/item_updater.cpp
index 03bc591..51523d4 100644
--- a/item_updater.cpp
+++ b/item_updater.cpp
@@ -12,7 +12,7 @@
 #include <experimental/filesystem>
 #include "version.hpp"
 #include "serialize.hpp"
-#include "image_verify.hpp"
+#include "images.hpp"
 
 namespace phosphor
 {