KVM: mmio: cleanup kvm_set_mmio_spte_mask

Just reuse rsvd_bits() inside kvm_set_mmio_spte_mask()
for slightly better code.

Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --cc arch/x86/kvm/mmu.c
Simple merge

diff --cc arch/x86/kvm/mmu.h
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge