selftests: kvm: update .gitignore with missing file

Fixes: d5edb7f8e7ab ("kvm: selftests: add vmx_tsc_adjust_test")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/kvm/.gitignore

@@ -1,2 +1,3 @@
 set_sregs_test
 sync_regs_test
+vmx_tsc_adjust_test