1. fix infinite loop problem when init phy device 2. fix infinite loop problem when reset mac 3. fix little bugs in ethernetif_init 4. fix incompatible return value between lwip and esp-idf Closes https://github.com/espressif/esp-idf/issues/2331 Closes https://github.com/espressif/esp-idf/issues/2141
This is to resolve issue reported in https://github.com/espressif/esp-idf/issues/130.
Move generic PHY support into its own interface