common: code re-org

Move common files under a common/ directory.

Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
Change-Id: I0eaf91d4ee94c1e78228da0c50892f82e91912fa
diff --git a/libpldmresponder/bios_string_attribute.cpp b/libpldmresponder/bios_string_attribute.cpp
index 1b6ba75..1453644 100644
--- a/libpldmresponder/bios_string_attribute.cpp
+++ b/libpldmresponder/bios_string_attribute.cpp
@@ -1,6 +1,6 @@
 #include "bios_string_attribute.hpp"
 
-#include "utils.hpp"
+#include "common/utils.hpp"
 
 #include <iostream>
 #include <tuple>