armv8/ls2085ardb: Add eth & phy firmware loading support

Add support for board eth initialization and support for loading phy
firmware. PHY firmware needs to be loaded from board_eth_init() because
all the MACs are not initialized by ldpaa_eth driver.

Signed-off-by: pankaj chauhan <pankaj.chauhan at freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar at freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>