wifi: mt76: connac: add support to set ifs time by mcu command

There's a race between driver and fw on some tx/rx control registers
when setting ifs, which will cause accidental hw queue pause problems.
Avoid this by setting ifs time with bss_info mcu command.

Reviewed-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>