MediaMetrics: Remove redundant heat map count variable

Test: adb shell dumpsys media.metrics
Bug: 199763036
Change-Id: I8503c1e4a8110c91d8776005d7282542e90c8fd7
diff --git a/services/mediametrics/HeatMap.h b/services/mediametrics/HeatMap.h
index 60a79b3..230d1ad 100644
--- a/services/mediametrics/HeatMap.h
+++ b/services/mediametrics/HeatMap.h
@@ -205,15 +205,14 @@
         std::stringstream ss;
         int32_t ll = lines;
         std::lock_guard l(mLock);
-        auto it = mMap.begin();
         if (ll > 0) {
             ss << "Error Heat Map (rejected: " << mRejected << "):\n";
             --ll;
         }
         // TODO: restriction is implemented alphabetically not on priority.
-        for (int32_t count = 0; it != mMap.end() && count < lines; ++count, ++it) {
+        for (const auto& [name, data] : mMap) {
             if (ll <= 0) break;
-            ss << it->first << ": " << it->second.dump() << "\n";
+            ss << name << ": " << data.dump() << "\n";
             --ll;
         }
         return { ss.str(), lines - ll };