Optimize Freezer deadlock detection

After removing MCP limitation, there could be much more apps cached in
the memmory. The overhead to check /proc/locks for each proces also
increases, causing more lock contentions.

Optimize it by checking /proc/locks once for adjacent freeze operations.

Bug: 276802031
Test: Check logcat and inotifyd /proc/locks
Change-Id: Ia65bb9d180c05d7ce2ff6a6382408c7e4eea2f4b