[OpenMP][NFC] Use `AsyncInfo` as the variable name for a `__tgt_async_info`

Reviewed By: grokos, tianshilei1992

Differential Revision: https://reviews.llvm.org/D96444

GitOrigin-RevId: 5449fbb5d49f8d7a8f9f2bdaab2c3b6b70fde31f
8 files changed