Log Message:

Add support for dual emac mode. In dual emac mode, the CPSW subsystem provides two independent ethernets. This is implemented (as recommended by TI's TRM) with a mixture of switch settings (vlans) and specific features of CPSW subsystem. The driver was splitted to accommodate the shared parts (RX and TX rings for example) while it still provides two independent ethernets. Each of the ethernet ports driver has it's own set of MDIO registers among the other private settings. Previously this driver always operate in promisc mode, now the Switch ALE (address table entry) is properly initialized and enabled. The driver is also tested (and known to work) with both ports operating in single port mode (active_slave 0 or 1). Tested on uBMC (dual emac mode, both ports in single mode, giga and fast ethernet) and BBB (single port, fast ethernet). Sponsored by: Rubicon Communications (Netgate)