Check dev-keystore to sign widevine apex

Bug: 310715038
Change-Id: I16dc21365d8ceb7ad1dd09afe88be91ef7db34ed
diff --git a/widevine/widevine.mk b/widevine/widevine.mk
index a8ffcc5..420806e 100644
--- a/widevine/widevine.mk
+++ b/widevine/widevine.mk
@@ -3,6 +3,9 @@
 
 ifdef RELEASE_PACKAGE_WIDEVINE
   PRODUCT_PACKAGES += $(RELEASE_PACKAGE_WIDEVINE)
+  ifneq ($(wildcard vendor/google/dev-keystore),)
+    $(call soong_config_set,widevine,use_devkey,true)
+  endif
   PRODUCT_VENDOR_LINKER_CONFIG_FRAGMENTS += \
 	vendor/widevine/libwvdrmengine/apex/device/linker.config.json
 else