Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot"

Revert "KVM: x86/mmu: Zap only the relevant pages when removing a memslot"

This reverts commit b16daaf306a2f92db0794396b8b87fb8c4c92b5a.
Alex Williamson reported regressions with device assignment with
this patch.  Even though the bug is probably elsewhere and still
latent, this is needed to fix the regression.

Fixes: b16daaf306a2 ("KVM: x86/mmu: Zap only the relevant pages when removing a memslot", 2019-02-05)
Reported-by: Alex Willamson <alex.williamson@redhat.com>
Cc: stable@vger.kernel.org
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>