ASoC: msm: Add support for stubbed hostless voice driver.

Stubbed hostless voice driver added to support use cases where
APQ QDSP6 voice module is not needed for voice calls.

Change-Id: I676726e6c704f1ee4cb078ed1b475a38afb8dc12
Signed-off-by: Neema Shetty <nshetty@codeaurora.org>
diff --git a/sound/soc/msm/msm-pcm-routing.h b/sound/soc/msm/msm-pcm-routing.h
index 5a93796..9515ab3 100644
--- a/sound/soc/msm/msm-pcm-routing.h
+++ b/sound/soc/msm/msm-pcm-routing.h
@@ -32,6 +32,8 @@
 #define LPASS_BE_SEC_I2S_RX "(Backend) SECONDARY_I2S_RX"
 
 #define LPASS_BE_MI2S_RX "(Backend) MI2S_RX"
+#define LPASS_BE_STUB_RX "(Backend) STUB_RX"
+#define LPASS_BE_STUB_TX "(Backend) STUB_TX"
 
 /* For multimedia front-ends, asm session is allocated dynamically.
  * Hence, asm session/multimedia front-end mapping has to be maintained.