kvm: Don't use VIRTIO_BLK_F_SEG_MAX in the hypervisor

kvm: Don't use VIRTIO_BLK_F_SEG_MAX in the hypervisor

We don't actually support VIRTIO_BLK_F_SEG_MAX so disable it from host
features. This fixes the following error during virtio block device probe in
the guest kernel which is caused by bogus "sg_elems" in virtblk_probe():

  ------------[ cut here ]------------
  WARNING: at mm/page_alloc.c:1968 __alloc_pages_nodemask+0x5b4/0x6c0()
  Modules linked in:
  Pid: 1, comm: swapper Not tainted 2.6.35-rc3 #48
  Call Trace:
   [<ffffffff81081e7f>] warn_slowpath_common+0x7f/0xc0
   [<ffffffff81081eda>] warn_slowpath_null+0x1a/0x20
   [<ffffffff8110a6e4>] __alloc_pages_nodemask+0x5b4/0x6c0
   [<ffffffff8124f860>] ? idr_get_empty_slot+0x110/0x2c0
   [<ffffffff8124f860>] ? idr_get_empty_slot+0x110/0x2c0
   [<ffffffff81138795>] alloc_page_interleave+0x45/0xa0
   [<ffffffff811395d9>] alloc_pages_current+0xb9/0xe0
   [<ffffffff8110993e>] __get_free_pages+0xe/0x50
   [<ffffffff8114191e>] __kmalloc+0x14e/0x1c0
   [<ffffffff8137dbf7>] ? virtio_config_buf+0x57/0x80
   [<ffffffff81671e15>] virtblk_probe+0x78/0x498

Signed-off-by: Pekka Enberg <penberg@kernel.org>