Add distortion output gain for Pixel 6.

The value will be used in HapticGenerator. The value is from UX
experiments.

Test: make
Bug: 193926091
Change-Id: I314aa5bc79ba756cdde4a03b0addd44eb69b27a3
diff --git a/device-raven.mk b/device-raven.mk
index 241ab91..71655bf 100644
--- a/device-raven.mk
+++ b/device-raven.mk
@@ -168,3 +168,7 @@
 PRODUCT_PACKAGES += \
 	android.hardware.bluetooth@1.1-service.bcmbtlinux \
 	bt_vendor.conf
+
+# Override default distortion output gain according to UX experiments
+PRODUCT_PRODUCT_PROPERTIES += \
+    vendor.audio.hapticgenerator.distortion.output.gain=0.5