hw/ivshmem: 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: NMarc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180625124238.25339-8-f4bug@amsat.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hw/misc/ivshmem.c

@@ -17,6 +17,7 @@
  * GNU GPL, version 2 or (at your option) any later version.
  */
 #include "qemu/osdep.h"
+#include "qemu/units.h"
 #include "qapi/error.h"
 #include "qemu/cutils.h"
 #include "hw/hw.h"
@@ -1301,7 +1302,7 @@ static void ivshmem_realize(PCIDevice *dev, Error **errp)
     }
 
     if (s->sizearg == NULL) {
-        s->legacy_size = 4 << 20; /* 4 MB default */
+        s->legacy_size = 4 * MiB; /* 4 MB default */
     } else {
         int ret;
         uint64_t size;