[U-Boot] efi: Use device device path type Messaging for network interface node

[Alexander Graf]

> When adding network interface node use Messaging device path with
> subtype MAC Address and device's MAC address as a value instead
> of Media Device path type with subtype File Path and path "Net"
> 
> Signed-off-by: Oleksandr Tymoshenko <gonzo at bluezbox.com>
> Cc: Alexander Graf <agraf at suse.de>

Thanks, applied to efi-next

Alex