wifi: mt76: mt7915: enable coredump support

Host triggered and catastrophic event triggered firmware core dumping
for basic firmware issues triage, including state reporting, task/irq
info, function calltrace and MCU memory dump.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>