Fix compile/link of init/do_mounts.c with !CONFIG_BLOCK

We need a stub function for when CONFIG_BLOCK isn't set.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index f589559..4c03ee3 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -434,6 +434,10 @@
 
 #endif
 
-#endif
+#else /* CONFIG_BLOCK */
+
+static inline void printk_all_partitions(void) { }
+
+#endif /* CONFIG_BLOCK */
 
 #endif