audio: update references to support prebuilt kernel build

Updating kernel references to LOCAL_ADDITIONAL_DEPENDENCIES and
BOARD_KERNEL_HEADER_DIR

Change-Id: I94fedd691dba7878b25c0ddbca0c87e62cbc856d
diff --git a/msm8909/hal/Android.mk b/msm8909/hal/Android.mk
index 2f85a31..848ee4e 100644
--- a/msm8909/hal/Android.mk
+++ b/msm8909/hal/Android.mk
@@ -44,6 +44,9 @@
 LOCAL_SRC_FILES += audio_extn/audio_extn.c \
                    audio_extn/utils.c
 
+LOCAL_C_INCLUDES += $(BOARD_KERNEL_HEADER_DIR)
+LOCAL_ADDITIONAL_DEPENDENCIES += $(BOARD_KERNEL_HEADER_DEPENDENCIES)
+
 ifeq ($(strip $(AUDIO_FEATURE_ENABLED_ASM_LOOPBACK_RX)),true)
   LOCAL_CFLAGS += -DASM_LOOPBACK_RX_ENABLED
 endif