TouchpadInputMapper: log when producing usage atoms

This should help us debug the flaky CTS tests for this atom.

Bug: 329725372
Test: check the log line appears when running the test:
      $ atest 'android.input.cts.hostside.InputAtomsTest#testTouchpadUsageAtom_FingerAndPalmCounts'
Change-Id: I23346b4904f83abb6cc5a07b687bb0a9802c6bfa
diff --git a/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp b/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp
index 99f9e24..721cdfd 100644
--- a/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/TouchpadInputMapper.cpp
@@ -198,6 +198,7 @@
     }
 
     void produceAtomsLocked(AStatsEventList& outEventList) const REQUIRES(mLock) {
+        ALOGI("Producing touchpad usage atoms for %zu counters", mCounters.size());
         for (auto& [id, counters] : mCounters) {
             auto [busId, vendorId, productId, versionId] = id;
             addAStatsEvent(&outEventList, android::util::TOUCHPAD_USAGE, vendorId, productId,