socfpga: add support for Terasic DE1-SoC board

Add CycloneV based Terasic DE1-SoC board. The board boots
from SD/MMC. Ethernet and USB host is supported.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Marek Vasut <marex@denx.de>
12 files changed