KVM: selftests: kvm_binary_stats_test: Fix index expressions

kvm_binary_stats_test accepts two arguments, the number of vms
and number of vcpus. If these inputs are not equal then the
test would likely crash for one reason or another due to using
miscalculated indices for the vcpus array. Fix the index
expressions by swapping the use of i and j.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Message-Id: <20220614081041.2571511-1-drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>