Revert "audio: exclude the echo reference device in capture position test"

This reverts commit b22f307c.

Reason for revert: As explained in b/192307382#comment12, the HAL must provide capture positions for the echo reference input regardless of whether there is any actual output.

This should not affect O6/R4 as according to b/192307382#comment10, the VTS tests pass w/o this patch after the HAL has been fixed.

Bug: 192307382
Change-Id: I224bd9de1dcb2e2c8dc138dbfd85f848378aea4f
Test: VtsHalAudioV7_0TargetTest --gtest_filter=*PcmOnlyConfigInputStreamTest*