ARM: socfpga: Add initial support for the ABB SECU board

Add initial support for the ABB SECU board, which is an ArriaV-based
SoCFPGA system with ethernet and booting from Denali NAND.

Signed-off-by: Holger Brunck <holger.brunck@ch.abb.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>