enic: fix tx_hang_reset use-after-free on device removal

enic: fix tx_hang_reset use-after-free on device removal

enic_remove() cancels the reset and change_mtu_work items but does not
cancel tx_hang_reset. A TX timeout that fires while the device is being
removed can schedule enic_tx_hang_reset() so that it runs after
free_netdev(), resulting in a use-after-free.

cancel_work_sync() alone is not sufficient here: the still-live watchdog
and notify paths can re-schedule these work items in the window between
the cancel and unregister_netdev(). Use disable_work_sync(), which
cancels the work and blocks any subsequent schedule_work() from
requeuing it, and apply it to the reset and change_mtu_work items as
well so the same requeue race is closed for all teardown work.

Fixes: 937317c7c109 ("enic: do hang reset only in case of tx timeout")
Signed-off-by: Satish Kharat <satishkh@cisco.com>
Link: https://patch.msgid.link/20260728062730.2394873-1-satishkh@cisco.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>