arm: socfpga: Add SoCFPGA SR1500 board

The SR1500 board is a CycloneV based board, similar to the EBV
SoCrates, equipped with the following devices:

- SPI NOR
- eMMC
- Ethernet

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Cc: Pavel Machek <pavel@denx.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Acked-by: Pavel Machek <pavel@denx.de>