arm: davinci: remove dead code for PHYs used by DaVinci DM* boards

The support for DaVinci DM* boards has been dropped a while ago. The
code for all those PHYs is no longer used and they have their own
proper PHY drivers in drivers/net/phy anyway. Remove all dead code.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>