gapps: Set ro.opa.eligible_device=true

This enables hotword detection for Google Assistant.

[Linux4: Make it overridable for devices where this breaks mic]

Change-Id: If1f7b77ca3ea907fceb945d7cdaf1bea253c00c9
diff --git a/gms.mk b/gms.mk
index fd57948..1216503 100644
--- a/gms.mk
+++ b/gms.mk
@@ -33,7 +33,8 @@
 
 ## GMS version
 PRODUCT_PRODUCT_PROPERTIES += \
-    ro.com.google.gmsversion=14_202310
+    ro.com.google.gmsversion=14_202310 \
+    ro.opa.eligible_device?=true
 
 ## Libraries
 PRODUCT_PACKAGES += \