Overlay part of the test_mmuhifi_c3 core has GPL3 copyright headers in
it. Fix that by regenerating test_mmuhifi_c3 core overlay and
re-importing it.
Fixes: d848ea7767 ("target/xtensa: add test_mmuhifi_c3 core")
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>