KVM: MMU: Store shadow page tables as kernel virtual addresses, not physical

Simpifies things a bit.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --cc drivers/kvm/kvm.h
Simple merge

diff --cc drivers/kvm/mmu.c
Simple merge

diff --cc drivers/kvm/paging_tmpl.h
Simple merge