libhwc2.1: don't construct string if debug log is disabled am: afbc2293eb

Original change: https://googleplex-android-review.googlesource.com/c/platform/hardware/google/graphics/zuma/+/24581795

Change-Id: I72202d0be25344fec75e1aff3496d4d0027de3df
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>