Clean up warnings in inputflinger.

Bug: http://b/26936282
Change-Id: Ie1fb281425c3b8c4b3e6e88dc5722d51b77ee093
diff --git a/services/inputflinger/InputDispatcher.cpp b/services/inputflinger/InputDispatcher.cpp
index 0fba1bf..87c96ce 100644
--- a/services/inputflinger/InputDispatcher.cpp
+++ b/services/inputflinger/InputDispatcher.cpp
@@ -134,7 +134,7 @@
     case AMOTION_EVENT_ACTION_POINTER_DOWN:
     case AMOTION_EVENT_ACTION_POINTER_UP: {
         int32_t index = getMotionEventActionPointerIndex(action);
-        return index >= 0 && size_t(index) < pointerCount;
+        return index >= 0 && index < pointerCount;
     }
     case AMOTION_EVENT_ACTION_BUTTON_PRESS:
     case AMOTION_EVENT_ACTION_BUTTON_RELEASE: