tools include UAPI: Sync linux/vhost.h with the kernel sources

To get the changes in:

  4c8cf318 ("vhost: introduce vDPA-based backend")

Silencing this perf build warning:

  Warning: Kernel ABI header at 'tools/include/uapi/linux/vhost.h' differs from latest version at 'include/uapi/linux/vhost.h'
  diff -u tools/include/uapi/linux/vhost.h include/uapi/linux/vhost.h

This automatically picks these new ioctls, making tools such as 'perf
trace' aware of them and possibly allowing to use the strings in
filters, etc:

  $ tools/perf/trace/beauty/vhost_virtio_ioctl.sh > before
  $ cp include/uapi/linux/vhost.h tools/include/uapi/linux/vhost.h
  $ tools/perf/trace/beauty/vhost_virtio_ioctl.sh > after
  $ diff -u before after
  --- before	2020-04-14 09:12:28.559748968 -0300
  +++ after	2020-04-14 09:12:38.781696242 -0300
  @@ -24,9 +24,16 @@
   	[0x44] = "SCSI_GET_EVENTS_MISSED",
   	[0x60] = "VSOCK_SET_GUEST_CID",
   	[0x61] = "VSOCK_SET_RUNNING",
  +	[0x72] = "VDPA_SET_STATUS",
  +	[0x74] = "VDPA_SET_CONFIG",
  +	[0x75] = "VDPA_SET_VRING_ENABLE",
   };
   static const char *vhost_virtio_ioctl_read_cmds[] = {
   	[0x00] = "GET_FEATURES",
   	[0x12] = "GET_VRING_BASE",
   	[0x26] = "GET_BACKEND_FEATURES",
  +	[0x70] = "VDPA_GET_DEVICE_ID",
  +	[0x71] = "VDPA_GET_STATUS",
  +	[0x73] = "VDPA_GET_CONFIG",
  +	[0x76] = "VDPA_GET_VRING_NUM",
   };
  $

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tiwei Bie <tiwei.bie@intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>