selftests: vm: update .gitignore with new test

Update .gitignore with new test.

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
index 63c94d7..342c7bc 100644
--- a/tools/testing/selftests/vm/.gitignore
+++ b/tools/testing/selftests/vm/.gitignore
@@ -11,3 +11,4 @@
 mlock-random-test
 virtual_address_range
 gup_benchmark
+va_128TBswitch