hw/arm/xilinx_zynq: Use the IEC binary prefix definitions

IEC binary prefixes ease code review: the unit is explicit.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: NAlistair Francis <alistair.francis@wdc.com>
Message-id: 20191021190653.9511-2-philmd@redhat.com
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/arm/xilinx_zynq.c

@@ -16,6 +16,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 #include "qapi/error.h"
 #include "cpu.h"
 #include "hw/sysbus.h"
@@ -194,7 +195,7 @@ static void zynq_init(MachineState *machine)
     memory_region_add_subregion(address_space_mem, 0, ext_ram);
 
     /* 256K of on-chip memory */
-    memory_region_init_ram(ocm_ram, NULL, "zynq.ocm_ram", 256 << 10,
+    memory_region_init_ram(ocm_ram, NULL, "zynq.ocm_ram", 256 * KiB,
                            &error_fatal);
     memory_region_add_subregion(address_space_mem, 0xFFFC0000, ocm_ram);