Make InCall wakelock non-reference counted

Certain orders of call state changes can lead to a non-symmetric
number of acquire and release calls. Make the wakelock non-reference
counted to ensure that wakelock is held deterministically based on
whether or not there is a ringing call present.

Bug: 24073449
Change-Id: Ie6807fa983016e3c70e2e047e2756000835ad5ec