wil6210: dump firmware memory when firmware crashes

When firmware crashes, just before firmware recovery,
dump the firmware memory to a devcoredump device.
The resulting dump can be read from user space to be used
in offline crash analysis.

Signed-off-by: Lior David <liord@codeaurora.org>
Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>