hal: fix voice call device routing issue

voice_device_set flag is to indicate voice call device routing
update from policymanager to HAL. It is set to true in voice_extn_start_call
and reset in update_calls() which causes mismatch in flag update during back
to back voice calls scenario. Update adev->voice_device_set flag in
voice_extn_stop_call instead of update_calls().

Bug: 17149385

Cherry-pick of CAF commit: e0085d06416a8fb6d0b4503900508c16fbc98c58

Change-Id: Ie07105671f254899890bdb4c0635c7dc1f55dbff