This makes is possible to use this SPI driver from other MVEBU SoC's as well.
As the upcoming Armada XP support will do.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
Tested-by: Luka Perkov <luka@openwrt.org>
Acked-by: Prafulla Wadaskar <prafulla@marvell.com>