selftests: kvm: add tsc_scaling_sync to .gitignore

The tsc_scaling_sync's binary should be present in the .gitignore
file for the git to ignore it.

Signed-off-by: Like Xu <likexu@tencent.com>
Message-Id: <20220406063715.55625-3-likexu@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/.gitignore

@@ -34,6 +34,7 @@
 /x86_64/state_test
 /x86_64/svm_vmcall_test
 /x86_64/svm_int_ctl_test
+/x86_64/tsc_scaling_sync
 /x86_64/sync_regs_test
 /x86_64/tsc_msrs_test
 /x86_64/userspace_io_test