PRODUCT_OTA_ENFORCE_VINTF_KERNEL_REQUIREMENTS: allow inheritance

Test: with this is true, build
     `verified_assembled_system_matrix.xml`;
      file includes kernel requirements
Change-Id: I833b4fefabefb2f0457171055afe5722981e3589
diff --git a/core/product.mk b/core/product.mk
index 661416c..df849b0 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -212,6 +212,7 @@
     PRODUCT_FORCE_PRODUCT_MODULES_TO_SYSTEM_PARTITION \
     PRODUCT_USE_DYNAMIC_PARTITIONS \
     PRODUCT_RETROFIT_DYNAMIC_PARTITIONS \
+    PRODUCT_OTA_ENFORCE_VINTF_KERNEL_REQUIREMENTS \
 
 define dump-product
 $(info ==== $(1) ====)\