Disable old Telephony updates when using PSTN Telecomm

This is a temporary workaround to allow PSTN Telecomm call services
and PSTN Telephony to co-exist. When a Telecomm PSTN call
is live we disable PSTN Telephony updates.

This prevents the old Telephony code from reacting to things like
incoming rings.

Change-Id: Ic283bed28005f534d337fefb47da445f2dc22c12
3 files changed