AudioDeviceBroker: fix regression in isValidCommunicationDevice

Commit 1dea0dab introduced a regression were the verification that the
device is a sink (output) device was removed from
isValidCommunicationDevice method.

Bug: 247659585
Bug: 266067856
Test: atest AudioCommunicationDeviceTest
Change-Id: Ie55debfeac1de21ef73c4de0f190cc77fa3b02be