migration: A rate limit value of 0 is valid

And it is the best way to not have rate_limit.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20230508130909.65420-2-quintela@redhat.com>

migration/migration.c

@@ -2140,12 +2140,7 @@ static int postcopy_start(MigrationState *ms)
      * will notice we're in POSTCOPY_ACTIVE and not actually
      * wrap their state up here
      */
-    /* 0 max-postcopy-bandwidth means unlimited */
-    if (!bandwidth) {
-        qemu_file_set_rate_limit(ms->to_dst_file, INT64_MAX);
-    } else {
-        qemu_file_set_rate_limit(ms->to_dst_file, bandwidth / XFER_LIMIT_RATIO);
-    }
+    qemu_file_set_rate_limit(ms->to_dst_file, bandwidth / XFER_LIMIT_RATIO);
     if (migrate_postcopy_ram()) {
         /* Ping just for debugging, helps line traces up */
         qemu_savevm_send_ping(ms->to_dst_file, 2);