KVM: MMU: Introduce init_kvm_nested_mmu()

This patch introduces the init_kvm_nested_mmu() function
which is used to re-initialize the nested mmu when the l2
guest changes its paging mode.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@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