In a situation when ION heap size is 0 dumpsys meminfo will not report ION memory usage. Fix this by differentiating 0-size ION heap or pool from the cases when /sys/kernel/ion/* do not exist or not readable. Bug: 168942451 Test: emulate 0-size ION heap and run dumpsys meminfo Signed-off-by: Suren Baghdasaryan <surenb@google.com> Change-Id: I66624c9e3c73a59462cce8830a36323677db0029