davinci: Add EMAC support for da850/omap-l138

Ethernet Media Access Controller (EMAC) on da850/omap-l138
supports 10/100 Mbps operation. It also supports Media
Independent Interface (MII) and Reduced Media Independent
Interface (RMII) to physical layer (PHY).

Phy which supports MII is present on the DA850/OMAP-L138
base board and Phy supporting RMII is present on the
UI card. This patch adds support only for the MII Phy.
Support for RMII Phy will be added later.

Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>