hal: voice: fix no sound issue in voice call

- no audio heard in voice call scenario because in_call state
  is not updated when voice usecase is stopped. This results in
  not starting voice call usecase when setting up next call.

- fix is to set in_call state to false in voice_stop_usecase().
  This is to ensure that voice usecase is stopped and in_call
  state is update properly.

Bug: 29581781
Change-Id: Id27f2b90cf0de678b39d8efb712045f1ee7b2aaf
diff --git a/hal/voice.c b/hal/voice.c
index d2215b6..f3250c9 100644
--- a/hal/voice.c
+++ b/hal/voice.c
@@ -124,8 +124,10 @@
     session->state.current = CALL_INACTIVE;
 
     /* Disable sidetone only when no calls are active */
-    if (!voice_is_call_state_active(adev))
+    if (!voice_is_call_state_active(adev)) {
+        adev->voice.in_call = false;
         voice_set_sidetone(adev, uc_info->out_snd_device, false);
+    }
 
     ret = platform_stop_voice_call(adev->platform, session->vsid);