[settings] Display "delete" option only for locally-originated settings

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/hci/tui/settings_ui.c

 	} else {
 		msg ( INSTRUCTION_ROW,
 		      "%sCtrl-X - exit configuration utility",
-		      ( widget->row.setting ?
+		      ( widget->row.originates_here ?
 			"Ctrl-D - delete setting" INSTRUCTION_PAD : "" ) );
 	}
 }