Commit 68ca0fd2 ("selftest/lkdtm: Don't pollute 'git status'")
introduced patterns for git to ignore files generated in
tools/testing/selftests/lkdtm/

Use local .gitignore file instead of using the root one.

Fixes: 68ca0fd2 ("selftest/lkdtm: Don't pollute 'git status'")
Signed-off-by: Christophe Leroy <[email protected]>
Acked-by: Kees Cook <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>