Add vendor_kernel_boot files to target-files-package

* This is a required dependency of target-files-package
so that it can be built from a clean build.

Test: rm -rf out/target/product && m target-files-package
Change-Id: I89e60f47e3e2cd6029a92b1aca505acd9cf4645b
diff --git a/core/Makefile b/core/Makefile
index f7a4ac0..ab96f87 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -6383,6 +6383,10 @@
   endif
 endif
 
+ifdef BUILDING_VENDOR_KERNEL_BOOT_IMAGE
+  $(BUILT_TARGET_FILES_DIR): $(INTERNAL_VENDOR_KERNEL_RAMDISK_FILES)
+endif
+
 ifdef BUILDING_RECOVERY_IMAGE
   # TODO(b/30414428): Can't depend on INTERNAL_RECOVERYIMAGE_FILES alone like other
   # BUILT_TARGET_FILES_PACKAGE dependencies because currently there're cp/rsync/rm