KVM: selftests: Explicitly free vcpus array in binary stats test

Explicitly free the all-encompassing vcpus array in the binary stats test
so that the test is consistent with respect to freeing all dynamically
allocated resources (versus letting them be freed on exit).

Link: https://lore.kernel.org/r/20230711230131.648752-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/kvm_binary_stats_test.c

@@ -236,6 +236,7 @@ int main(int argc, char *argv[])
 	for (i = 0; i < max_vm; ++i)
 		kvm_vm_free(vms[i]);
 	free(vms);
+	free(vcpus);
 
 	ksft_finished();	/* Print results and exit() accordingly */
 }