Api Change: do not configure ethernet mac addresses by default

In order to simplify the Mac Address handling within Drv_Eth the behavior of Drv_Eth will be changed as follows:

• Drv_Eth_Backends initialize all mac addresses with the XPEC with 00:00:00:00:00:00
• Drv_Eth_Backends do not load Mac Addresses from Dataprovider or Security Memory
• It is the task of the application to set the Mac Addresses to correct values before activating the Bus. The Ioctl Api shall be used for this
• It is strongly recommended, that the application does not change the Mac Address configuration after the first activation of the bus. (Devices must not change the Mac Address at runtime)