audio: Fix compilation issue

Add audio-driver headers files path to search
directory list during compilation process.

Change-Id: Ie7c5b50a7bcdfb62af33f83dec64936c6b53cabf
diff --git a/hal/Makefile.am b/hal/Makefile.am
index 95224d0..46882f1 100644
--- a/hal/Makefile.am
+++ b/hal/Makefile.am
@@ -4,6 +4,7 @@
         -I $(top_srcdir)/hal \
         -I $(top_srcdir)/hal/audio_extn \
         -I $(top_srcdir)/hal/voice_extn \
+        -I $(PKG_CONFIG_SYSROOT_DIR)/usr/include/audio-kernel \
         -I $(top_srcdir)/hal/${TARGET_PLATFORM}
 
 c_sources = audio_hw.c \