hal: Support Multichannel Speaker playback

Until now speaker playback only supports stereo
and is limited to default sample rate.
Update code to support QCS405 configurations with
CSRA soundcards that can have up to 16 or 32 speaker
output channels and allow sample rates up to 384kHz.

Change-Id: Ib4ed5edafca6f8b15134ca66db4bf1ef719ec15d
diff --git a/hal/msm8974/platform.h b/hal/msm8974/platform.h
index c8ddaec..e1f433c 100644
--- a/hal/msm8974/platform.h
+++ b/hal/msm8974/platform.h
@@ -280,6 +280,8 @@
 
 #define AUDIO_PARAMETER_KEY_TRUE_32_BIT "true_32_bit"
 
+#define AUDIO_MAX_DSP_CHANNELS 32
+
 #define ALL_SESSION_VSID                0xFFFFFFFF
 #define DEFAULT_MUTE_RAMP_DURATION_MS   20
 #define DEFAULT_VOLUME_RAMP_DURATION_MS 20