wifi: mt76: mt7925: fix fails to enter low power mode in suspend state

wifi: mt76: mt7925: fix fails to enter low power mode in suspend state

The mt7925 sometimes fails to enter low power mode during suspend.
This is caused by the chip firmware sending an additional ACK event
to the host after processing the suspend command. Due to timing issues,
this event may not reach the host, causing the chip to get stuck.
To resolve this, the ACK flag in the suspend command is removed,
as it is not needed in the MT7925 architecture. This prevents the
firmware from sending the additional ACK event, ensuring the device
can reliably enter low power mode during suspend.

Signed-off-by: Quan Zhou <quan.zhou@mediatek.com>
Link: https://patch.msgid.link/d056938144a3a0336c3a4e3cec6f271899f32bf7.1736775666.git.quan.zhou@mediatek.com
Signed-off-by: Felix Fietkau <nbd@nbd.name>