ASoC: msm: Add support for ASM loopback

Add ASM loopback driver. When audio path wants to use filters in DSP,
it will do a loopback in ASM.  The new ASM loopback driver enables
the loopback.

Change-Id: I3ddfbf0a1be5b3b1d37b47b44d321ea7da93da83
Signed-off-by: Damir Didjusto <damird@codeaurora.org>
Signed-off-by: Vimal Puthanveed <vimalp@codeaurora.org>
Signed-off-by: flar2 <asegaert@gmail.com>