Fix TaskRecord wrong dump element firstActiveTime

[Cause of Defect]
Used wrong class field.

Test: manual - adb shell dumpsys activity a

Change-Id: I6f54e374709b6ae60f8adabd5c29a1f100941c42
Signed-off-by: daqi <daqi@xiaomi.com>
diff --git a/services/core/java/com/android/server/am/TaskRecord.java b/services/core/java/com/android/server/am/TaskRecord.java
index 4691e1a..abbdd54 100644
--- a/services/core/java/com/android/server/am/TaskRecord.java
+++ b/services/core/java/com/android/server/am/TaskRecord.java
@@ -1777,7 +1777,7 @@
         pw.print(prefix + "hasBeenVisible=" + hasBeenVisible);
                 pw.print(" mResizeMode=" + ActivityInfo.resizeModeToString(mResizeMode));
                 pw.print(" isResizeable=" + isResizeable());
-                pw.print(" firstActiveTime=" + lastActiveTime);
+                pw.print(" firstActiveTime=" + firstActiveTime);
                 pw.print(" lastActiveTime=" + lastActiveTime);
                 pw.println(" (inactive for " + (getInactiveDuration() / 1000) + "s)");
     }