KVM: MMU: Rename variables of type 'struct kvm_mmu_page *'

These are traditionally named 'page', but even more traditionally, that name
is reserved for variables that point to a 'struct page'.  Rename them to 'sp'
(for "shadow page").

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

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