polaris: Override vendor's usb_audio_policy_configuration

Android 8.1 added the support for new type of USB Audio devices
(USB_HEADSET, instead of old USB_DEVICE)
Some older USB devices got converted to this USB_HEADSET while still
using the old protocol.
There is no driver change needed, but the audio policy needs to be
changed.
Since vendors are simply using AOSP usb_audio_policy_configuration
Override it by ourself.

Change-Id: I5c43cd7c95f721914cf94f4dc20c992b4f6a24e9

device.mk

@@ -28,6 +28,10 @@ PRODUCT_AAPT_PREF_CONFIG := xxhdpi
 # Inherit from sdm845-common
 $(call inherit-product, device/xiaomi/sdm845-common/sdm845.mk)
 
+# Audio
+PRODUCT_COPY_FILES += \
+    frameworks/av/services/audiopolicy/config/usb_audio_policy_configuration.xml:system/etc/usb_audio_policy_configuration.xml
+
 # Device init scripts
 PRODUCT_PACKAGES += \
     init.target.rc

rootdir/etc/init.target.rc

@@ -1,2 +1,3 @@
 on init
     mount none /system/bin/time_daemon /vendor/bin/time_daemon bind
+    mount none /system/etc/usb_audio_policy_configuration.xml /vendor/etc/usb_audio_policy_configuration.xml bind

sepolicy/private/file_contexts

@@ -1,2 +1,5 @@
+# Audio
+/system/etc/usb_audio_policy_configuration.xml    u:object_r:vendor_configs_file:s0
+
 # Time services
 /system/bin/time_daemon         u:object_r:time_daemon_exec:s0

sepolicy/private/init.te

@@ -1,2 +1,5 @@
 # Allow init to bind mount time_daemon
 allow init time_daemon_exec:file mounton;
+
+# Allow init to mount vendor configs
+allow init vendor_configs_file:file mounton;