binder: Add copyright notice to new kunit files

Clean up for the binder_alloc kunit test series. Add a copyright notice
to new files, as suggested by Carlos [1].

[1] https://lore.kernel.org/all/CAFuZdDLD=3CBOLSWw3VxCf7Nkf884SSNmt1wresQgxgBwED=eQ@mail.gmail.com/



Fixes: 5e024582 ("binder: Scaffolding for binder_alloc KUnit tests")
Suggested-by: Carlos Llamas <cmllamas@google.com>
Cc: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Tiffany Yang <ynaffit@google.com>
Link: https://lore.kernel.org/r/20250722234508.232228-1-ynaffit@google.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>