Revert "dts: socfpga: Add DTS entry for adding the stmmac glue layer for stmmac."

This reverts commit 7e0b4cd0

.

The binding changes need to be done differently as well, let's
take them through netdev, and merge the dts changes in a new
patch here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>