netdev: driver: ethernet: Add TI CPSW driver

This patch adds support for TI's CPSW driver.

The three port switch gigabit ethernet subsystem provides ethernet packet
communication and can be configured as an ethernet switch. Supports
10/100/1000 Mbps.

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Sriramakrishnan A G <srk@ti.com>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>