llvm_tools: fix `cros lint` & mypy issues in patch_utils

`mypy` doesn't infer the right types for some of these lists, and
_really_ dislikes multiple calls to the same Callable with different
signatures.

`cros lint` was unhappy with `==` to compare fns, and unmentioned things
in docstrings.

BUG=b:332589934
TEST=repo upload

Change-Id: Ic6929e8524797b2fdc96db65a94c0f98ea9dd8bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/5420774
Commit-Queue: George Burgess <gbiv@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Tested-by: George Burgess <gbiv@chromium.org>
2 files changed