KVM: MMU: Adjust pte accessors to explicitly indicate guest or shadow pte

Since the guest and host ptes can have wildly different format, adjust
the pte accessor names to indicate on which type of pte they operate on.

No functional changes.

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/paging_tmpl.h
Simple merge

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