net: Add TI DaVinci EMAC driver

Add support for TI DaVinci EMAC driver.

TI DaVinci Ethernet Media Access Controller module is based upon
TI CPPI 3.0 DMA engine and supports 10/100 Mbps on all and Gigabit modes on
some TI devices. It supports MII/RMII and has up to 8Kbytes of internal
descriptor memory. This driver has been working on several TI devices including
DM644x, DM646x and DA830 platforms. The specs of this device are available at:
http://www.ti.com/litv/pdf/sprue24a



Signed-off-by: Anant Gole <anantgole@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>