wifi: mwifiex: fix use-after-free in mwifiex_adapter_cleanup()

wifi: mwifiex: fix use-after-free in mwifiex_adapter_cleanup()

The mwifiex_adapter_cleanup() function uses timer_delete()
(non-synchronous) for the wakeup_timer before the adapter structure is
freed. This is incorrect because timer_delete() does not wait for any
running timer callback to complete.

If the wakeup_timer callback (wakeup_timer_fn) is executing when
mwifiex_adapter_cleanup() is called, the callback will continue to
access adapter fields (adapter->hw_status, adapter->if_ops.card_reset,
etc.) which may be freed by mwifiex_free_adapter() called later in the
mwifiex_remove_card() path.

Use timer_delete_sync() instead to ensure any running timer callback has
completed before returning.

Fixes: 4636187da60b ("mwifiex: add wakeup timer based recovery mechanism")
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Hodges <git@danielhodges.dev>
Link: https://patch.msgid.link/20260206194401.2346-1-git@danielhodges.dev
Signed-off-by: Johannes Berg <johannes.berg@intel.com>