topology: aw88399: add explicit deepbuffer route to smart amp

Add explicit route from mixin.15.1 (deepbuffer pipeline) to mixout.20.1
(AW88399 smart amp pipeline) so PCM 31 audio flows through the smart
amplifiers instead of only through HDA analog codec.

This enables the external AW88399 amplifiers to be used for deepbuffer
playback, providing full-range audio instead of tweeter-only output.

Signed-off-by: Yakov Till <yakov.till@gmail.com>

Author: Lyapsus

tools/topology/topology2/sof-hda-generic-aw88399.conf

@@ -83,12 +83,6 @@ IncludeByKey.HDA_CONFIG {
 	"passthrough"	"cavs-passthrough-hda.conf"
 }
 
-# Override deepbuffer to route through AW88399 smart amp instead of HDA analog
-# MUST be after HDA_CONFIG include so it overrides the HDA config's Define block
-Define {
-	DEEP_BUFFER_PIPELINE_SINK	'mixout.20.1'
-}
-
 # include DMIC config if needed.
 IncludeByKey.NUM_DMICS {
 	"[1-4]"	"platform/intel/dmic-generic.conf"
@@ -275,6 +269,11 @@ Object.Base.route [
 	{
 		source 'mixin.1.1'
 		sink 'mixout.20.1'
+	}
+	{
+		# Route deepbuffer (PCM 31) through AW88399 smart amp
+		source 'mixin.15.1'
+		sink 'mixout.20.1'
 	}
 		{
 			source 'smart_amp.20.1'