perf pmu-events: Fix jevents.py type annotations for mypy 2.x

Since the build runs mypy whenever it is installed, the perf build fails
with mypy 2.4 on 7 errors in jevents.py, e.g.:

  pmu-events/jevents.py:542: error: Item "None" of "str | None" has no
  attribute "replace"  [union-attr]
  pmu-events/jevents.py:563: error: Item "None" of "BigCString | None"
  has no attribute "offsets"  [union-attr]

Both come from wrong annotations rather than from code that can see
None:
 - unit_to_pmu() is annotated as returning Optional[str] but always
   returns a string, so JsonEvent.pmu is typed as optional where it is
   used as a str.
 - _bcs is set to None before the BigCString class is defined and only
   assigned an instance after it, so mypy types it as BigCString | None.

Correct the return type and declare _bcs with its type instead of the
None placeholder. The generated pmu-events.c and pmu-events-string.c
are unchanged, and mypy 1.9 still passes.

Fixes: b3e9c396d0acab27 ("perf build: Make mypy build test opt-out (NO_MYPY=1)")
Signed-off-by: Lalit Maganti <lalitmaganti@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Assisted-by: LLM
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

0 files changed, 0 insertions, 0 deletions