ARM: socfpga: Correct SCU virtual mapping in socfpga

Correct SCU virtual mapping that was causing this BUG message:

"BUG: mapping for 0xfffec000 at 0xfffec000 out of vmalloc space"

Signed-off-by: Vince Bridgers <vbridger@opensource.altera.com>
Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>