kernel: Mediatek: set default EEE Tx LPI timer

kernel: Mediatek: set default EEE Tx LPI timer

Due to API changes during the backport, the default value of Tx LPI
timer is accidentally left unset, breaking the network if EEE is on.
Set the default timer to 1ms on init, and fix an incorrect condition.

Fixes: d8315d5358d5 ("kernel: backport Mediatek SoC EEE support")
Signed-off-by: Qingfang Deng <dqfext@gmail.com>