Merge branch 'tun-timer-cleanups'

Eric Dumazet says:

====================
tun: timer cleanups

While working on a syzkaller issue that might have been
fixed already by Cong Wang in commit 0ad646c8
("tun: call dev_get_valid_name() before register_netdevice()")
I made three small changes related to flow_gc_timer.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>