The "#ifdef SUNXI_SPC_BASE" guard was meant to allow the build on SoCs
without a Secure Peripherals Controller, so that we skip that part of
the security setup. But in the current position this will trigger a
warning about an unused variable.

Simply move the guard one line up to cover the variable as well.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>