NetworkPkg: Print error message to screen if error occurs during HTTP boot.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>

NetworkPkg/HttpDxe/HttpImpl.c

@@ -523,6 +523,7 @@ EfiHttpRequest (
       
       FreePool (HostNameStr);
       if (EFI_ERROR (Status)) {
+        DEBUG ((EFI_D_ERROR, "Error: Could not retrieve the host address from DNS server.\n"));
         goto Error1;
       }
     }