bios: Converting bios json keys to lower snake case

Converting following bios attribute json keys to lower snake case
displayName --> display_name
helpText    --> help_text
readOnly    --> read_only

Tested:
     Power on/off
     Gtest passed

Change-Id: Iad88ed7bc381d66182c99e31e7d385f65750e0ed
Signed-off-by: Archana Kakani <archana.kakani@ibm.com>
diff --git a/libpldmresponder/test/libpldmresponder_bios_attribute_test.cpp b/libpldmresponder/test/libpldmresponder_bios_attribute_test.cpp
index 93b633a..7f07d6d 100644
--- a/libpldmresponder/test/libpldmresponder_bios_attribute_test.cpp
+++ b/libpldmresponder/test/libpldmresponder_bios_attribute_test.cpp
@@ -46,9 +46,9 @@
 {
     auto jsonReadOnly = R"({
       "attribute_name" : "ReadOnly",
-      "readOnly" : true,
-      "helpText" : "HelpText",
-      "displayName" : "DisplayName"
+      "read_only" : true,
+      "help_text" : "HelpText",
+      "display_name" : "DisplayName"
     })"_json;
 
     TestAttribute readOnly{jsonReadOnly, nullptr};
@@ -64,9 +64,9 @@
 
     auto jsonReadWrite = R"({
       "attribute_name":"ReadWrite",
-      "readOnly" : false,
-      "helpText" : "HelpText",
-      "displayName" : "DisplayName",
+      "read_only" : false,
+      "help_text" : "HelpText",
+      "display_name" : "DisplayName",
       "dbus":
            {
                "object_path" : "/xyz/abc/def",