Increase GetTotalTicks() to uint64_t

For larger networks the GetTotalTicks() might overflow if the function
returns int32_t. GetTotalTicks() is a non virtual function that can
be overridden with a different return type in the implementation class.

Change-Id: I8dd2e448fd13e0823fe1e5f9cc335998d2806416
diff --git a/lib/arm_profiler/include/arm_profiler.hpp b/lib/arm_profiler/include/arm_profiler.hpp
index 36adb8d..0b97e2e 100644
--- a/lib/arm_profiler/include/arm_profiler.hpp
+++ b/lib/arm_profiler/include/arm_profiler.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2022 Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: Apache-2.0
  *
@@ -30,7 +30,7 @@
     ArmProfiler(size_t max_events = 200);
     uint32_t BeginEvent(const char *tag);
     void EndEvent(uint32_t event_handle);
-    int32_t GetTotalTicks() const;
+    uint64_t GetTotalTicks() const;
 
 private:
     size_t max_events_;