mt76: mt7921: always wake the device in mt7921_remove_interface

Make sure the mcu is not in sleep mode before sending mcu messages in
mt7921_remove_interface routine.

Fixes: 1d8efc74

 ("mt76: mt7921: introduce Runtime PM support")
Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Co-developed-by: Leon Yen <leon.yen@mediatek.com>
Signed-off-by: Leon Yen <leon.yen@mediatek.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>