wifi: mt76: mt7921e: stop chip reset worker in unregister hook

If the chip reset worker is triggered during the remove process, the chip
DMA may not be properly pushed back to the idle state. This can lead to
corruption of the DMA flow due to the chip reset. Therefore, it is
necessary to stop the chip reset before the DMA is finalized.

To avoid resetting the chip after the reset worker is cancelled, use
__mt7921_mcu_drv_pmctrl() instead of mt7921_mcu_drv_pmctrl(). It is safe to
ignore the pm mutex because the pm worker and wake worker have already been
cancelled.

Fixes: 033ae79b

 ("mt76: mt7921: refactor init.c to be bus independent")
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Co-developed-by: Deren Wu <deren.wu@mediatek.com>
Signed-off-by: Deren Wu <deren.wu@mediatek.com>
Co-developed-by: Wang Zhao <wang.zhao@mediatek.com>
Signed-off-by: Wang Zhao <wang.zhao@mediatek.com>
Signed-off-by: Quan Zhou <quan.zhou@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>