tests/qtest/test-hmp: Fix migrate_set_parameter xbzrle-cache-size test

The command always fails with "Error: Parameter 'xbzrle_cache_size'
expects a power of two no less than the target page size".  The test
passes anyway.  Change the argument from 1 to 64k to make the test a
bit more useful.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

tests/qtest/test-hmp.c

@@ -45,7 +45,7 @@ static const char *hmp_cmds[] = {
     "log all",
     "log none",
     "memsave 0 4096 \"/dev/null\"",
-    "migrate_set_parameter xbzrle-cache-size 1",
+    "migrate_set_parameter xbzrle-cache-size 64k",
     "migrate_set_parameter downtime-limit 1",
     "migrate_set_parameter max-bandwidth 1",
     "netdev_add user,id=net1",