Remove tools/codespell

In the end, we found it to be not useful enough to have
this in our code repos, so remove the submodule dep.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
tools/check_patch: Remove reference to codespell submodule

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>