wifi: mt76: mt792x: Fix a potential deadlock in high-load situations

wifi: mt76: mt792x: Fix a potential deadlock in high-load situations

A deadlock may occur between two works, ps_work and mac_work, if their work
functions run simultaneously as they attempt to cancel each other by
calling cancel_delayed_work_sync().

mt792x_mac_work() ->   ...  -> cancel_delayed_work_sync(&pm->ps_work);
mt792x_pm_power_save_work() -> cancel_delayed_work_sync(&mphy->mac_work);

In high-load situations, they are queued but may not have chance to be
executed until the CPUs are released. Once the CPUs are available, there
is a high possibility that the ps_work function and mac_work function will
be executed simultaneously, resulting in a possible deadlock.

This patch replaces cancel_delayed_work_sync() with cancel_delayed_work()
in ps_work to eliminate the deadlock and make the code easier to maintain.

Signed-off-by: Leon Yen <leon.yen@mediatek.com>
Tested-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
Link: https://patch.msgid.link/20251215122231.3180648-1-leon.yen@mediatek.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>