qxl: set default values of vram*_size_mb to -1

The addition of those values caused a regression where not specifying
any value for the vram bar size would result in a 4096 _byte_ surface
area. This is ok for the windows driver but causes the X driver to be
unusable. Also, it's a regression. This patch returns the default
behavior of having a 64 megabyte vram BAR.
Signed-off-by: NAlon Levy <alevy@redhat.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/qxl.c

@@ -1959,8 +1959,8 @@ static Property qxl_properties[] = {
         DEFINE_PROP_UINT32("guestdebug", PCIQXLDevice, guestdebug, 0),
         DEFINE_PROP_UINT32("cmdlog", PCIQXLDevice, cmdlog, 0),
         DEFINE_PROP_UINT32("ram_size_mb",  PCIQXLDevice, ram_size_mb, -1),
-        DEFINE_PROP_UINT32("vram_size_mb", PCIQXLDevice, vram32_size_mb, 0),
-        DEFINE_PROP_UINT32("vram64_size_mb", PCIQXLDevice, vram_size_mb, 0),
+        DEFINE_PROP_UINT32("vram_size_mb", PCIQXLDevice, vram32_size_mb, -1),
+        DEFINE_PROP_UINT32("vram64_size_mb", PCIQXLDevice, vram_size_mb, -1),
         DEFINE_PROP_END_OF_LIST(),
 };