It is harmless because all users pass 'a' to this macro.

Fixes: 00175aec ("net/sched: Macro instead of CONFIG_NET_CLS_ACT ifdef")
Cc: Amir Vadai <amir@vadai.me>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Acked-by: NJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>