hal: Add support for IMS calls

Move all the voice call specific code to a new file.
Add voice extension files to support IMS calls.

Change-Id: I1b7235500c8e3c2285b726b351d996dc3e5ebdf6
diff --git a/hal/msm8960/platform.h b/hal/msm8960/platform.h
index a2ae80f..4d137aa 100644
--- a/hal/msm8960/platform.h
+++ b/hal/msm8960/platform.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013 The Android Open Source Project
+ * Copyright (C) 2013-2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.