wlan vendor propose a feature to check the refcnt of netdev when
interface register/unregister. Add `netdev_refcnt_read` into symbol
list.
Adding the following symbols:
- netdev_refcnt_read
Bug: 340118509
Change-Id: I6a2ad4bbfa13d01011729b764dfe92f4945a829e
Signed-off-by: Hsiu-Chang Chen <hsiuchangchen@google.com>