ARM: dts: mdm9630: add stub DAIs to device tree

DTMF and host pcm stub DAIs are added to device tree to
support DTMF detection and voice host pcm features.

Change-Id: Idb49dc42c4a7c8b2a3b157684f99615b84fb15eb
Signed-off-by: Helen Zeng <xiaoyunz@codeaurora.org>