dsp: add voice MHI driver

Add voice MHI driver to support the following features -
1. Allocate and map mailbox memory needed for voice call
packet exchange.
2. Send memory mapped addresses to ADSP.
3. Vote MHI host driver at start and stop of a voice call.

Change-Id: I8ef8bc270acacab9b80bca7addccdf73bd572adf
Signed-off-by: Vikram Panduranga <vpandura@codeaurora.org>
diff --git a/dsp/q6_init.c b/dsp/q6_init.c
index e97a496..1078c57 100644
--- a/dsp/q6_init.c
+++ b/dsp/q6_init.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2017, The Linux Foundation. All rights reserved.
-*/
+ * Copyright (c) 2017, 2019 The Linux Foundation. All rights reserved.
+ */
 
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -22,6 +22,7 @@
 	audio_slimslave_init();
 	avtimer_init();
 	msm_mdf_init();
+	voice_mhi_init();
 	return 0;
 }
 
@@ -40,6 +41,7 @@
 	rtac_exit();
 	audio_cal_exit();
 	adsp_err_exit();
+	voice_mhi_exit();
 }
 
 module_init(audio_q6_init);