Use knob->prompt for DisplayName in BiosAttributeRegistry

GET on /redfish/v1/Registries/BiosAttributeRegistry/BiosAttributeRegistry/
shows list of Attributes under RegistryEntries. Each attribute
corresponds to a knob in BIOS.

DisplayName is currently filled with knob->name but knob->prompt is more
accurate for DisplayName as that is the name we see in EDKII menu.

Code changes makes the above mentioned fix.

Tested
Sample knobs from BIOS.
<knob name="ADDDCEn" prompt="ADDDC Sparing" ... >
	<options>
		<option text="Disable" value="0x0"/>
		<option text="Enable" value="0x1"/>
	</options>
</knob>

Corresponding Redfish response in BiosAttributeRegistry
{
	"AttributeName": "ADDDCEn",
	"CurrentValue": "0x00",
	"DefaultValue": "0x00",
	"DisplayName": "ADDDC Sparing",
	"HelpText": "Enable/Disable ADDDC Sparing",
	"MenuPath": "./",
	"ReadOnly": false,
	"Type": "Enumeration",
	"Value": [
		{
			"ValueDisplayName": "Disable",
			"ValueName": "0x0"
		},
		{
			"ValueDisplayName": "Enable",
			"ValueName": "0x1"
		}
	]
}

Change-Id: I6ee251e32169cecb4d86436373397054863552b5
Signed-off-by: Arun Lal K M <arun.lal@intel.com>
diff --git a/include/biosxml.hpp b/include/biosxml.hpp
index f11d42a..1936a01 100644
--- a/include/biosxml.hpp
+++ b/include/biosxml.hpp
@@ -686,7 +686,7 @@
                 bios::BiosBaseTableTypeEntry baseTableEntry = std::make_tuple(
                     "xyz.openbmc_project.BIOSConfig.Manager.AttributeType."
                     "Enumeration",
-                    false, knob.nameStr, knob.descriptionStr, "./",
+                    false, knob.promptStr, knob.descriptionStr, "./",
                     knob.currentValStr, knob.defaultStr, options);
 
                 baseTable.emplace(knob.nameStr, baseTableEntry);