hw/i386/xen/xen-hvm: Use the IEC binary prefix definitions

IEC binary prefixes ease code review: the unit is explicit.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200601142930.29408-8-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

hw/i386/xen/xen-hvm.c

@@ -9,6 +9,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 
 #include "cpu.h"
 #include "hw/pci/pci.h"
@@ -230,7 +231,7 @@ static void xen_ram_init(PCMachineState *pcms,
          * Xen does not allocate the memory continuously, it keeps a
          * hole of the size computed above or passed in.
          */
-        block_len = (1ULL << 32) + x86ms->above_4g_mem_size;
+        block_len = (4 * GiB) + x86ms->above_4g_mem_size;
     }
     memory_region_init_ram(&ram_memory, NULL, "xen.ram", block_len,
                            &error_fatal);