Please include d391f120706726826 in v4.9.y [x86/kvm/vmx]: do not use vm-exit instruction length for fast MMIO when running nested

[Mike Haboustak <haboustak@xxxxxxxxx>]

The following commit fixes freezes in virtio device drivers when KVM
is nested under
VMWare Workstation/ESXi or Hyper-V. I've encountered problems running KVM
inside VMWare since upgrading to Debian 9 (currently testing 4.9.88-1+deb9u1).

d391f1207067268261add0485f0f34503539c5b0

The same issue affects 4.4.y as well.  A git-bisect within my
environment stopped at
e9ea5069d9e569c32ab913c39467df32e056b3a7, where the KVM capability was added
that QEMU checks before enabling fast mmio.

Thanks,
Mike