ThemeManager: Synchronize access to listeners

If the Set of listeners is modified while iterating we will get
a ConcurentModificationException so we need to synchronize access
to avoid this.

Change-Id: Ib521ad86a665316d707463200c16c1bcdcfac362
Revert 'base: Add P2P interface "p2p0" to tethering support list'

* fixes p2p issues

Change-Id: I12249f4f633c5b317d04da9f433ee58bb21f4681