This API is based on a block structure with a 8 Byte large
API v3 header and various of different blocks following. It extends
our current API v2, which is always 32 Byte large, and is located
directly after v2.
Add the MAC block as first block type. It contains the physical
Ehternet interface number, a MAC address and a CRC checksum over the
MAC payload.
Signed-off-by: Daniel Schultz <d.schultz@phytec.de> Tested-by: Wadim Egorov <w.egorov@phytec.de>