phylib: convert state_queue work to delayed_work

phylib: convert state_queue work to delayed_work

It closes a race in phy_stop_machine when reprogramming of phy_timer
(from phy_state_machine) happens between del_timer_sync and cancel_work_sync.

Without this change it could lead to crash if phy_device would be freed after
phy_stop_machine (timer would fire and schedule freed work).

Signed-off-by: Marcin Slusarz <[email protected]>
Acked-by: Jean Delvare <[email protected]>
Signed-off-by: David S. Miller <[email protected]>