KVM: selftests: Drop "all done!" printf() from PERF_CAPABILITIES test

Drop the arbitrary "done" message from the VMX PMU caps test, it's pretty
obvious the test is done when the process exits.

Link: https://lore.kernel.org/r/20230311004618.920745-19-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

tools/testing/selftests/kvm/x86_64/vmx_pmu_caps_test.c

@@ -213,6 +213,4 @@ int main(int argc, char *argv[])
 	test_fungible_perf_capabilities(host_cap);
 	test_immutable_perf_capabilities(host_cap);
 	test_guest_wrmsr_perf_capabilities(host_cap);
-
-	printf("Completed perf capability tests.\n");
 }