audio policy: add missing encapsulation type default init in AudioProfile

The AudioProfile class has 3 constructors and one of them was not
initializing mEncapsulationType member.

Bug: 186719136
Test: run gts -a armeabi-v7a -m GtsGmscoreHostTestCases -t com.google.android.gts.audio.AudioHostTest#testTwoChannelCapturingCheckSubmixDevice
Change-Id: Ic7ecc9cfa28f7da2856b38d444f66c7808d36557