dragonboard: pixel3_mainline: Include firmware/device.mk if available am: 8a11a96d35

Change-Id: Ic3f100cb8f6a285a0bba2265a6e772a127706b15
diff --git a/pixel3_mainline/device.mk b/pixel3_mainline/device.mk
index aab118b..a6d53f0 100644
--- a/pixel3_mainline/device.mk
+++ b/pixel3_mainline/device.mk
@@ -28,3 +28,6 @@
 
 # Build generic Audio HAL
 PRODUCT_PACKAGES := audio.primary.pixel3_mainline
+
+# Copy firmware files
+$(call inherit-product-if-exists, $(LOCAL_PATH)/firmware/device.mk)