Add Multicast wakelock stats in battery-stats dump

This commit adds the statistics for multicast wakelocks (count/time)
in dump of battery-stats.
This enables debugging of power issues due to extensive wakeup of host
processor due to arrival of multicast packets, and help identify the
blamed application

Bug: 33649966
Test: Manual Test
Change-Id: I882f945dd36fa2881c59776b4954017bf3c76cd7
Signed-off-by: Ahmed ElArabawy <arabawy@google.com>