ARM: zynq: Reserve correct amount of non-DMA RAM

On Zynq, we haven't been reserving the correct amount of DMA-incapable
RAM to keep DMA away from it (per the Zynq TRM Section 4.1, it should be
the first 512k). In older kernels, this was masked by the
memblock_reserve call in arm_memblock_init(). Now, reserve the correct
amount excplicitly rather than relying on swapper_pg_dir, which is an
address and not a size anyway.

Fixes: 46f5b960 ("ARM: zynq: Reserve not DMAable space in front of the
kernel")
Signed-off-by: Kyle Roeschley <kyle.roeschley@ni.com>
Tested-by: Nathan Rossi <nathan@nathanrossi.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/mach-zynq/common.c

@@ -59,7 +59,7 @@ void __iomem *zynq_scu_base;
 static void __init zynq_memory_init(void)
 {
 	if (!__pa(PAGE_OFFSET))
-		memblock_reserve(__pa(PAGE_OFFSET), __pa(swapper_pg_dir));
+		memblock_reserve(__pa(PAGE_OFFSET), 0x80000);
 }
 
 static struct platform_device zynq_cpuidle_device = {