hwc2: add locks for callback functions am: 4c3b62c9a8 am: 16355d4be3

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/qcom/sm8150/display/+/11835313

Change-Id: Ie98b17db2488ce3bef156a7a6b8370ed4cd15ce1