ASoC: msm: Set NULL topology for voice call recording

Default topolgy consumes higher MIPS in in-call voice rec-
ording. Set NULL topolgoy to reduce the MIPS consumption.

Change-Id: Iaa19092459f8c7861ae1ae1a742d12485bb37b74
Signed-off-by: Venkata Narendra Kumar Gutta <vgutta@codeaurora.org>