hw/riscv: Use the IEC binary prefix definitions

It eases code review, unit is explicit.

Patch generated using:

  $ git grep -E '(1024|2048|4096|8192|(<<|>>).?(10|20|30))' hw/ include/hw/

and modified manually.
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NMichael Clark <mjc@sifive.com>
Message-Id: <20180625124238.25339-17-f4bug@amsat.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/riscv/virt.c

@@ -19,6 +19,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 #include "qemu/log.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
@@ -84,7 +85,7 @@ static hwaddr load_initrd(const char *filename, uint64_t mem_size,
      * halfway into RAM, and for boards with 256MB of RAM or more we put
      * the initrd at 128MB.
      */
-    *start = kernel_entry + MIN(mem_size / 2, 128 * 1024 * 1024);
+    *start = kernel_entry + MIN(mem_size / 2, 128 * MiB);
 
     size = load_ramdisk(filename, *start, mem_size - *start);
     if (size == -1) {