KVM: x86: Fix a typo in Documentation/virt/kvm/x86/mmu.rst

L1 CR4.LA57 should be '0' instead of '1' when shadowing 5-level NPT
for 4-level NPT L1 guest.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://lore.kernel.org/r/20230518091339.1102-4-binbin.wu@linux.intel.com


Signed-off-by: Sean Christopherson <seanjc@google.com>