BIOS: Modify to support BIOS string type

Modify the definitions of constructAttrTable() to make it more convenient
to construct different type data together.

Change-Id: I607966eeaac888a9bd863cedcc80ce819f5b34d8
Signed-off-by: Carol Wang <wangkair@cn.ibm.com>
diff --git a/libpldmresponder/bios_parser.hpp b/libpldmresponder/bios_parser.hpp
index 0e21991..1f13f94 100644
--- a/libpldmresponder/bios_parser.hpp
+++ b/libpldmresponder/bios_parser.hpp
@@ -32,6 +32,8 @@
 {
 
 using Strings = std::vector<std::string>;
+inline constexpr auto bIOSEnumJson = "enum_attrs.json";
+inline constexpr auto bIOSStrJson = "string_attrs.json";
 
 /** @brief Parse every BIOS configuration JSON files in the directory path
  *         and populate all the attribute names and all the preconfigured