tests: numa: test one backend with prealloc enabled

Cannibalize one backend in the HMAT test to make sure that
prealloc=y is tested.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20200325094423.24293-3-imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tests/qtest/numa-test.c

@@ -455,7 +455,7 @@ static void pc_hmat_off_cfg(const void *data)
     cli = make_cli(data, "-nodefaults --preconfig "
                          "-smp 2,sockets=2 "
                          "-m 128M,slots=2,maxmem=1G "
-                         "-object memory-backend-ram,size=64M,id=m0 "
+                         "-object memory-backend-ram,size=64M,id=m0,prealloc=y "
                          "-object memory-backend-ram,size=64M,id=m1 "
                          "-numa node,nodeid=0,memdev=m0");
     qs = qtest_init(cli);