mt76: mt7921: forbid the doze mode when coredump is in progress

We forbid the doze mode while the collecting core dump is going because
that doesn't make sense and the firmware possibly stays in the abnormal
state where cannot handle the doze request from the driver anymore until
the WiFi reset procedure is completed.

Co-developed-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: YN Chen <YN.Chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>