Fix incorrect in-call notification

There was an issue where the in-call notification would still show
content appropriate for a ringing call. The in-call UI may be showing
before Telecom has updated the call to the active state, so it may be
the case that state can be Call.State.Incoming while notificationType is
NOTIFICATION_IN_CALL. Since the contents of the notification are mostly
dependent on state, this causes a mismatch between the contents of the
notification and notificationType.

Thus, a notification may be displayed that has the contents of a ringing
call notification, but it will store NOTIFICATION_IN_CALL into
mCurrentNotification. When the call gets updated to the active state,
the previous notification will not be cleared, resulting in the
incorrect behavior.

Bug: 25598950
Change-Id: Ic0b3700587322b8d3cf0787a724577e58e0bb701