raven: enable frame rate override feature

Bug: 176940105
Test: atest FrameRateOverrideHostTest
Change-Id: I88f4f54cbb930a68ef45a7ec01e587b410d63e97
diff --git a/device-raven.mk b/device-raven.mk
index f01b71e..4b9788f 100644
--- a/device-raven.mk
+++ b/device-raven.mk
@@ -33,6 +33,7 @@
 include hardware/google/pixel/vibrator/cs40l25/device.mk
 
 PRODUCT_DEFAULT_PROPERTY_OVERRIDES += ro.surface_flinger.support_kernel_idle_timer=true
+PRODUCT_DEFAULT_PROPERTY_OVERRIDES += ro.surface_flinger.enable_frame_rate_override=true
 
 # Init files
 PRODUCT_COPY_FILES += \