efi_loader: implement ConvertDeviceNodeToText

efi_loader: implement ConvertDeviceNodeToText

Move the logic for converting a node to text from
efi_convert_device_path_to_text to convert_device_node_to_text.

Provide a wrapper function convert_device_node_to_text_ext.

As we use only shallow device paths so we can call
directly call efi_device_node_to_text from efi_device_path_to_text.

Add output for MAC addresses.

Add output for not yet supported types/subtypes.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>