Fix Wcast-function-type-mismatch

```
packages/modules/Bluetooth/system/osi/src/alarm.cc:674:36: error: cast from 'void (*)(void *)' to 'void (*)(union sigval)' converts to incompatible function type [-Werror,-Wcast-function-type-mismatch]
  674 |   sigevent.sigev_notify_function = (void (*)(union sigval))timer_callback;
      |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
```

Bug: 353528991
Test: m checkbuild
Flag: Exempt refactor no-op
Change-Id: I533dd21af0a8ec3bad019777d4e8e6950b52b603