[ddk][docs] Correct comment for device_add_args.flags

Test: docs only

Change-Id: Ib67cf051fcb2f41167c2dbf715e5fb07388d2cad
diff --git a/system/ulib/ddk/include/ddk/driver.h b/system/ulib/ddk/include/ddk/driver.h
index 81e9cb1..4596907 100644
--- a/system/ulib/ddk/include/ddk/driver.h
+++ b/system/ulib/ddk/include/ddk/driver.h
@@ -98,7 +98,7 @@
     // the proxy device in the new devhost
     const char* proxy_args;
 
-    // One or more of DEVICE_ADD_*
+    // Zero or more of DEVICE_ADD_*
     uint32_t flags;
 
     // Optional channel passed to the |dev| that serves as an open connection for the client.