KVM: Remove ptr comparisons to 0

Fix sparse warnings "Using plain integer as NULL pointer"

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

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

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

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